String.LastIndexOf Metoda

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

public:
 int LastIndexOf(System::String ^ value, int startIndex, int count, StringComparison comparisonType);

public int LastIndexOf (string value, int startIndex, int count, StringComparison comparisonType);

member this.LastIndexOf : string * int * int * StringComparison -> int

Public Function LastIndexOf (value As String, startIndex As Integer, count As Integer, comparisonType As StringComparison) As Integer

Parametry

Návraty

Pozice počátečního indexu založeného na nule value parametru, pokud je tento řetězec nalezen, nebo -1 pokud není nalezena nebo pokud aktuální instance se rovná Empty.

Výjimky

Příklady

Následující příklad ukazuje tři přetížení LastIndexOf metoda, které najdou poslední výskyt řetězce v jiném řetězci pomocí různých hodnot StringComparison výčtu.

// This code example demonstrates the 
// System.String.LastIndexOf(String, ..., StringComparison) methods.

using System;
using System.Threading;
using System.Globalization;

class Sample 
{
    public static void Main() 
    {
    string intro = "Find the last occurrence of a character using different " + 
                   "values of StringComparison.";
    string resultFmt = "Comparison: {0,-28} Location: {1,3}";

// Define a string to search for.
// U+00c5 = LATIN CAPITAL LETTER A WITH RING ABOVE
    string CapitalAWithRing = "\u00c5"; 

// Define a string to search. 
// The result of combining the characters LATIN SMALL LETTER A and COMBINING 
// RING ABOVE (U+0061, U+030a) is linguistically equivalent to the character 
// LATIN SMALL LETTER A WITH RING ABOVE (U+00e5).
    string cat = "A Cheshire c" + "\u0061\u030a" + "t";
    int loc = 0;
    StringComparison[] scValues = {
        StringComparison.CurrentCulture,
        StringComparison.CurrentCultureIgnoreCase,
        StringComparison.InvariantCulture,
        StringComparison.InvariantCultureIgnoreCase,
        StringComparison.Ordinal,
        StringComparison.OrdinalIgnoreCase };

// Clear the screen and display an introduction.
    Console.Clear();
    Console.WriteLine(intro);

// Display the current culture because culture affects the result. For example, 
// try this code example with the "sv-SE" (Swedish-Sweden) culture.

    Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");
    Console.WriteLine("The current culture is \"{0}\" - {1}.", 
                       Thread.CurrentThread.CurrentCulture.Name,
                       Thread.CurrentThread.CurrentCulture.DisplayName);

// Display the string to search for and the string to search.
    Console.WriteLine("Search for the string \"{0}\" in the string \"{1}\"", 
                       CapitalAWithRing, cat);
    Console.WriteLine();

// Note that in each of the following searches, we look for 
// LATIN CAPITAL LETTER A WITH RING ABOVE in a string that contains 
// LATIN SMALL LETTER A WITH RING ABOVE. A result value of -1 indicates 
// the string was not found.
// Search using different values of StringComparsion. Specify the start 
// index and count. 

    Console.WriteLine("Part 1: Start index and count are specified.");
    foreach (StringComparison sc in scValues)
        {
        loc = cat.LastIndexOf(CapitalAWithRing, cat.Length-1, cat.Length, sc);
        Console.WriteLine(resultFmt, sc, loc);
        }

// Search using different values of StringComparsion. Specify the 
// start index. 
    Console.WriteLine("\nPart 2: Start index is specified.");
    foreach (StringComparison sc in scValues)
        {
        loc = cat.LastIndexOf(CapitalAWithRing, cat.Length-1, sc);
        Console.WriteLine(resultFmt, sc, loc);
        }

// Search using different values of StringComparsion. 
    Console.WriteLine("\nPart 3: Neither start index nor count is specified.");
    foreach (StringComparison sc in scValues)
        {
        loc = cat.LastIndexOf(CapitalAWithRing, sc);
        Console.WriteLine(resultFmt, sc, loc);
        }
    }
}

/*
Note: This code example was executed on a console whose user interface 
culture is "en-US" (English-United States).

This code example produces the following results:

Find the last occurrence of a character using different values of StringComparison.
The current culture is "en-US" - English (United States).
Search for the string "Å" in the string "A Cheshire ca°t"

Part 1: Start index and count are specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

Part 2: Start index is specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

Part 3: Neither start index nor count is specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

*/

// This code example demonstrates the
// System.String.LastIndexOf(String, ..., StringComparison) methods.

open System
open System.Threading
open System.Globalization

let intro = "Find the last occurrence of a character using different values of StringComparison."

// Define a string to search for.
// U+00c5 = LATIN CAPITAL LETTER A WITH RING ABOVE
let CapitalAWithRing = "\u00c5"

// Define a string to search.
// The result of combining the characters LATIN SMALL LETTER A and COMBINING
// RING ABOVE (U+0061, U+030a) is linguistically equivalent to the character
// LATIN SMALL LETTER A WITH RING ABOVE (U+00e5).
let cat = "A Cheshire c" + "\u0061\u030a" + "t"
let loc = 0
let scValues = 
    [| StringComparison.CurrentCulture
       StringComparison.CurrentCultureIgnoreCase
       StringComparison.InvariantCulture
       StringComparison.InvariantCultureIgnoreCase
       StringComparison.Ordinal
       StringComparison.OrdinalIgnoreCase  |]

// Clear the screen and display an introduction.
Console.Clear()
printfn $"{intro}"

// Display the current culture because culture affects the result. For example,
// try this code example with the "sv-SE" (Swedish-Sweden) culture.

Thread.CurrentThread.CurrentCulture <- CultureInfo "en-US"
printfn $"The current culture is \"{Thread.CurrentThread.CurrentCulture.Name}\" - {Thread.CurrentThread.CurrentCulture.DisplayName}."

// Display the string to search for and the string to search.
printfn $"Search for the string \"{CapitalAWithRing}\" in the string \"{cat}\"\n"

// Note that in each of the following searches, we look for
// LATIN CAPITAL LETTER A WITH RING ABOVE in a string that contains
// LATIN SMALL LETTER A WITH RING ABOVE. A result value of -1 indicates
// the string was not found.
// Search using different values of StringComparsion. Specify the start
// index and count.

printfn "Part 1: Start index and count are specified."
for sc in scValues do
    let loc = cat.LastIndexOf(CapitalAWithRing, cat.Length-1, cat.Length, sc)
    printfn $"Comparison: {sc,-28} Location: {loc,3}"

// Search using different values of StringComparsion. Specify the
// start index.
printfn "\nPart 2: Start index is specified."
for sc in scValues do
    let loc = cat.LastIndexOf(CapitalAWithRing, cat.Length-1, sc)
    printfn $"Comparison: {sc,-28} Location: {loc,3}"

// Search using different values of StringComparsion.
printfn "\nPart 3: Neither start index nor count is specified."
for sc in scValues do
    let loc = cat.LastIndexOf(CapitalAWithRing, sc)
    printfn $"Comparison: {sc,-28} Location: {loc,3}"

(*
Note: This code example was executed on a console whose user interface
culture is "en-US" (English-United States).

This code example produces the following results:

Find the last occurrence of a character using different values of StringComparison.
The current culture is "en-US" - English (United States).
Search for the string "Å" in the string "A Cheshire ca°t"

Part 1: Start index and count are specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

Part 2: Start index is specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

Part 3: Neither start index nor count is specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

*)

' This code example demonstrates the 
' System.String.LastIndexOf(String, ..., StringComparison) methods.

Imports System.Threading
Imports System.Globalization

Class Sample
    Public Shared Sub Main() 
        Dim intro As String = "Find the last occurrence of a character using different " & _
                              "values of StringComparison."
        Dim resultFmt As String = "Comparison: {0,-28} Location: {1,3}"
        
        ' Define a string to search for.
        ' U+00c5 = LATIN CAPITAL LETTER A WITH RING ABOVE
        Dim CapitalAWithRing As String = "Å"
        
        ' Define a string to search. 
        ' The result of combining the characters LATIN SMALL LETTER A and COMBINING 
        ' RING ABOVE (U+0061, U+030a) is linguistically equivalent to the character 
        ' LATIN SMALL LETTER A WITH RING ABOVE (U+00e5).
        Dim cat As String = "A Cheshire c" & "å" & "t"
        Dim loc As Integer = 0
        Dim scValues As StringComparison() =  { _
                        StringComparison.CurrentCulture, _
                        StringComparison.CurrentCultureIgnoreCase, _
                        StringComparison.InvariantCulture, _
                        StringComparison.InvariantCultureIgnoreCase, _
                        StringComparison.Ordinal, _
                        StringComparison.OrdinalIgnoreCase }
        Dim sc As StringComparison
        
        ' Clear the screen and display an introduction.
        Console.Clear()
        Console.WriteLine(intro)
        
        ' Display the current culture because culture affects the result. For example, 
        ' try this code example with the "sv-SE" (Swedish-Sweden) culture.
        Thread.CurrentThread.CurrentCulture = New CultureInfo("en-US")
        Console.WriteLine("The current culture is ""{0}"" - {1}.", _
                           Thread.CurrentThread.CurrentCulture.Name, _
                           Thread.CurrentThread.CurrentCulture.DisplayName)
        
        ' Display the string to search for and the string to search.
        Console.WriteLine("Search for the string ""{0}"" in the string ""{1}""", _
                           CapitalAWithRing, cat)
        Console.WriteLine()
        
        ' Note that in each of the following searches, we look for 
        ' LATIN CAPITAL LETTER A WITH RING ABOVE in a string that contains 
        ' LATIN SMALL LETTER A WITH RING ABOVE. A result value of -1 indicates 
        ' the string was not found.
        ' Search using different values of StringComparsion. Specify the start 
        ' index and count. 
        Console.WriteLine("Part 1: Start index and count are specified.")
        For Each sc In  scValues
            loc = cat.LastIndexOf(CapitalAWithRing, cat.Length - 1, cat.Length, sc)
            Console.WriteLine(resultFmt, sc, loc)
        Next sc
        
        ' Search using different values of StringComparsion. Specify the 
        ' start index. 
        Console.WriteLine(vbCrLf & "Part 2: Start index is specified.")
        For Each sc In  scValues
            loc = cat.LastIndexOf(CapitalAWithRing, cat.Length - 1, sc)
            Console.WriteLine(resultFmt, sc, loc)
        Next sc
        
        ' Search using different values of StringComparsion. 
        Console.WriteLine(vbCrLf & "Part 3: Neither start index nor count is specified.")
        For Each sc In  scValues
            loc = cat.LastIndexOf(CapitalAWithRing, sc)
            Console.WriteLine(resultFmt, sc, loc)
        Next sc
    
    End Sub
End Class

'
'Note: This code example was executed on a console whose user interface 
'culture is "en-US" (English-United States).
'
'This code example produces the following results:
'
'Find the last occurrence of a character using different values of StringComparison.
'The current culture is "en-US" - English (United States).
'Search for the string "Å" in the string "A Cheshire ca°t"
'
'Part 1: Start index and count are specified.
'Comparison: CurrentCulture               Location:  -1
'Comparison: CurrentCultureIgnoreCase     Location:  12
'Comparison: InvariantCulture             Location:  -1
'Comparison: InvariantCultureIgnoreCase   Location:  12
'Comparison: Ordinal                      Location:  -1
'Comparison: OrdinalIgnoreCase            Location:  -1
'
'Part 2: Start index is specified.
'Comparison: CurrentCulture               Location:  -1
'Comparison: CurrentCultureIgnoreCase     Location:  12
'Comparison: InvariantCulture             Location:  -1
'Comparison: InvariantCultureIgnoreCase   Location:  12
'Comparison: Ordinal                      Location:  -1
'Comparison: OrdinalIgnoreCase            Location:  -1
'
'Part 3: Neither start index nor count is specified.
'Comparison: CurrentCulture               Location:  -1
'Comparison: CurrentCultureIgnoreCase     Location:  12
'Comparison: InvariantCulture             Location:  -1
'Comparison: InvariantCultureIgnoreCase   Location:  12
'Comparison: Ordinal                      Location:  -1
'Comparison: OrdinalIgnoreCase            Location:  -1
'

Poznámky

Číslování indexů začíná od nuly. To znamená, že první znak v řetězci je na nule indexu a poslední je v Length - 1.

Hledání začíná na pozici startIndex znaku a pokračuje zpět, dokud se nenajde value nebo count pozice znaků. Pokud je například startIndexLength - 1, metoda vyhledá zpětně count znaky od posledního znaku v řetězci.

Parametr comparisonType určuje, že se má vyhledat parametr value pomocí:

• Aktuální nebo invariantní jazyková verze.
• Vyhledávání nerozlišuje velká a malá a velká písmena.
• Pravidla porovnávání slov nebo řadových pravidel

Poznámky pro volající

Znakové sady obsahují ignorovatelné znaky, což jsou znaky, které se při provádění jazykového nebo jazykového porovnání nerozlišují. V hledání citlivém na jazykovou verzi (to znamená, že pokud comparisonType není Ordinal nebo OrdinalIgnoreCase), pokud value obsahuje ignorovatelný znak, je výsledek ekvivalentní hledání s tímto znakem odebraným.

V následujícím příkladu se metoda LastIndexOf(String, Int32, Int32, StringComparison) používá k vyhledání pozice měkkého spojovníku (U+00AD) následovaného znakem "m" ve všech kromě první pozice znaku před posledním znakem "m" ve dvou řetězcích. Požadovaný podřetězc obsahuje pouze jeden z řetězců. Pokud je příklad spuštěn v rozhraní .NET Framework 4 nebo novější, v obou případech, protože měkký spojovník je ignorovatelný znak, metoda vrátí index "m" v řetězci, když provede porovnání s jazykovou verzí. Když však provede řadové porovnání, najde podřetězce pouze v prvním řetězci. Všimněte si, že v případě prvního řetězce, který obsahuje měkké pomlčky následované "m", metoda vrátí index "m", když provede porovnání citlivé na jazykovou verzi. Metoda vrátí index měkkého spojovníku v prvním řetězci pouze při provádění pořadového porovnání.

string searchString = "\u00ADm";

string s1 = "ani\u00ADmal";
string s2 = "animal";

int position;

position = s1.LastIndexOf('m');
if (position >= 1)
{
    Console.WriteLine(s1.LastIndexOf(searchString, position, position, StringComparison.CurrentCulture));
    Console.WriteLine(s1.LastIndexOf(searchString, position, position, StringComparison.Ordinal));
}

position = s2.LastIndexOf('m');
if (position >= 1)
{
    Console.WriteLine(s2.LastIndexOf(searchString, position, position, StringComparison.CurrentCulture));
    Console.WriteLine(s2.LastIndexOf(searchString, position, position, StringComparison.Ordinal));
}

// The example displays the following output:
//
// 4
// 3
// 3
// -1

let searchString = "\u00ADm"

let s1 = "ani\u00ADmal"
let s2 = "animal"

let position = s1.LastIndexOf 'm'
if position >= 1 then
    printfn $"{s1.LastIndexOf(searchString, position, position, StringComparison.CurrentCulture)}"
    printfn $"{s1.LastIndexOf(searchString, position, position, StringComparison.Ordinal)}"

let position = s2.LastIndexOf 'm'
if position >= 1 then
    printfn $"{s2.LastIndexOf(searchString, position, position, StringComparison.CurrentCulture)}"
    printfn $"{s2.LastIndexOf(searchString, position, position, StringComparison.Ordinal)}"

// The example displays the following output:
//
// 4
// 3
// 3
// -1

Dim searchString As String = ChrW(&HAD) + "m"

Dim s1 As String = "ani" + ChrW(&HAD) + "m"
Dim s2 As String = "animal"

Dim position As Integer

position = s1.LastIndexOf("m"c)
If position >= 1 Then
    Console.WriteLine(s1.LastIndexOf(searchString, position, position, StringComparison.CurrentCulture))
    Console.WriteLine(s1.LastIndexOf(searchString, position, position, StringComparison.Ordinal))
End If

position = s2.LastIndexOf("m"c)
If position >= 1 Then
    Console.WriteLine(s2.LastIndexOf(searchString, position, position, StringComparison.CurrentCulture))
    Console.WriteLine(s2.LastIndexOf(searchString, position, position, StringComparison.Ordinal))
End If

' The example displays the following output:
'
' 4
' 3
' 3
' -1

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

public:
 int LastIndexOf(System::String ^ value, int startIndex, int count);

public int LastIndexOf (string value, int startIndex, int count);

member this.LastIndexOf : string * int * int -> int

Public Function LastIndexOf (value As String, startIndex As Integer, count As Integer) As Integer

Parametry

Návraty

Pozice počátečního indexu založeného na nule value, pokud se tento řetězec najde, nebo -1, pokud se nenajde nebo pokud se aktuální instance rovná Empty.

Výjimky

Příklady

Následující příklad najde index všech výskytů řetězce v podřetězci, který pracuje od konce podřetězce až po začátek podřetězce.

// Sample for String::LastIndexOf(String, Int32, Int32)
using namespace System;
int main()
{
   String^ br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-";
   String^ br2 = "0123456789012345678901234567890123456789012345678901234567890123456";
   String^ str = "Now is the time for all good men to come to the aid of their party.";
   int start;
   int at;
   int count;
   int end;
   start = str->Length - 1;
   end = start / 2 - 1;
   Console::WriteLine( "All occurrences of 'he' from position {0} to {1}.", start, end );
   Console::WriteLine( "{1}{0}{2}{0}{3}{0}", Environment::NewLine, br1, br2, str );
   Console::Write( "The string 'he' occurs at position(s): " );
   count = 0;
   at = 0;
   while ( (start > -1) && (at > -1) )
   {
      count = start - end; //Count must be within the substring.
      at = str->LastIndexOf( "he", start, count );
      if ( at > -1 )
      {
         Console::Write( "{0} ", at );
         start = at - 1;
      }
   }

   Console::Write( "{0} {0} {0}", Environment::NewLine );
}

/*
This example produces the following results:
All occurrences of 'he' from position 66 to 32.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The string 'he' occurs at position(s): 56 45
*/

// Sample for String.LastIndexOf(String, Int32, Int32)
using System;

class Sample {
    public static void Main() {

    string br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-";
    string br2 = "0123456789012345678901234567890123456789012345678901234567890123456";
    string str = "Now is the time for all good men to come to the aid of their party.";
    int start;
    int at;
    int count;
    int end;

    start = str.Length-1;
    end = start/2 - 1;
    Console.WriteLine("All occurrences of 'he' from position {0} to {1}.", start, end);
    Console.WriteLine("{1}{0}{2}{0}{3}{0}", Environment.NewLine, br1, br2, str);
    Console.Write("The string 'he' occurs at position(s): ");

    count = 0;
    at = 0;
    while((start > -1) && (at > -1))
        {
        count = start - end; //Count must be within the substring.
        at = str.LastIndexOf("he", start, count);
        if (at > -1)
            {
            Console.Write("{0} ", at);
            start = at - 1;
            }
        }
    Console.Write("{0}{0}{0}", Environment.NewLine);
    }
}
/*
This example produces the following results:
All occurrences of 'he' from position 66 to 32.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The string 'he' occurs at position(s): 56 45
*/

// Sample for String.LastIndexOf(String, Int32, Int32)
open System

let br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-"
let br2 = "0123456789012345678901234567890123456789012345678901234567890123456"
let str = "Now is the time for all good men to come to the aid of their party."

let mutable start = str.Length-1
let last = start / 2 - 1
printfn $"All occurrences of 'he' from position {start} to {last}."
printfn $"{br1}{Environment.NewLine}{br2}{Environment.NewLine}{str}{Environment.NewLine}"
printf "The string 'he' occurs at position(s): "

let mutable at = 0
while (start > -1) && (at > -1) do
    let count = start - last //Count must be within the substring.
    at <- str.LastIndexOf("he", start, count)
    if at > -1 then
        printf $"{at} "
        start <- at - 1
printf $"{Environment.NewLine}{Environment.NewLine}{Environment.NewLine}"
(*
This example produces the following results:
All occurrences of 'he' from position 66 to 32.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The string 'he' occurs at position(s): 56 45
*)

' Sample for String.LastIndexOf(String, Int32, Int32)
 _

Class Sample
   
   Public Shared Sub Main()
      
      Dim br1 As String = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-"
      Dim br2 As String = "0123456789012345678901234567890123456789012345678901234567890123456"
      Dim str As String = "Now is the time for all good men to come to the aid of their party."
      Dim start As Integer
      Dim at As Integer
      Dim count As Integer
      Dim [end] As Integer

      start = str.Length - 1
      [end] = start / 2 - 1
      Console.WriteLine("All occurrences of 'he' from position {0} to {1}.", start, [end])
      Console.WriteLine("{1}{0}{2}{0}{3}{0}", Environment.NewLine, br1, br2, str)
      Console.Write("The string 'he' occurs at position(s): ")
      
      count = 0
      at = 0
      While start > - 1 And at > - 1
         count = start - [end] 'Count must be within the substring.
         at = str.LastIndexOf("he", start, count)
         If at > - 1 Then
            Console.Write("{0} ", at)
            start = at - 1
         End If
      End While
      Console.Write("{0}{0}{0}", Environment.NewLine)
   End Sub
End Class
'
'This example produces the following results:
'All occurrences of 'he' from position 66 to 32.
'0----+----1----+----2----+----3----+----4----+----5----+----6----+-
'0123456789012345678901234567890123456789012345678901234567890123456
'Now is the time for all good men to come to the aid of their party.
'
'The string 'he' occurs at position(s): 56 45
'
'

Poznámky

Číslování indexů začíná od nuly. To znamená, že první znak v řetězci je na nule indexu a poslední je v Length - 1.

Hledání začíná na startIndex pozici znaku této instance a pokračuje směrem k začátku, dokud se nenajde value nebo count pozice znaků. Pokud je například startIndexLength - 1, metoda vyhledá zpětně count znaky od posledního znaku v řetězci.

Tato metoda provádí hledání slov (rozlišujících velká a malá písmena a jazykové verze) pomocí aktuální jazykové verze.

Znakové sady obsahují ignorovatelné znaky, což jsou znaky, které se při provádění jazykového nebo jazykového porovnání nerozlišují. Pokud v hledání citlivém na jazykovou verzi value obsahuje ignorovatelný znak, výsledek odpovídá hledání s odebraným znakem.

V následujícím příkladu se metoda LastIndexOf používá k vyhledání pozice měkkého spojovníku (U+00AD) následovaného znakem "m" nebo "n" ve dvou řetězcích. Pouze jeden z řetězců obsahuje měkké pomlčky. V případě řetězce, který obsahuje měkké pomlčky následované znakem "m", LastIndexOf vrátí index "m" při hledání měkkého spojovníku následovaného znakem "m".

int position = 0;
string s1 = "ani\u00ADmal";
string s2 = "animal";

// Find the index of the soft hyphen followed by "n".
position = s1.LastIndexOf("m");
Console.WriteLine($"'m' at position {position}");

if (position >= 0)
    Console.WriteLine(s1.LastIndexOf("\u00ADn", position, position + 1));

position = s2.LastIndexOf("m");
Console.WriteLine($"'m' at position {position}");

if (position >= 0)
    Console.WriteLine(s2.LastIndexOf("\u00ADn", position, position + 1));

// Find the index of the soft hyphen followed by "m".
position = s1.LastIndexOf("m");
Console.WriteLine($"'m' at position {position}");

if (position >= 0)
    Console.WriteLine(s1.LastIndexOf("\u00ADm", position, position + 1));

position = s2.LastIndexOf("m");
Console.WriteLine($"'m' at position {position}");

if (position >= 0)
    Console.WriteLine(s2.LastIndexOf("\u00ADm", position, position + 1));

// The example displays the following output:
//
// 'm' at position 4
// 1
// 'm' at position 3
// 1
// 'm' at position 4
// 4
// 'm' at position 3
// 3

let s1 = "ani\u00ADmal"
let s2 = "animal"

// Find the index of the soft hyphen followed by "n".
let position = s1.LastIndexOf "m"
printfn $"'m' at position {position}"

if position  >= 0 then
    printfn $"""{s1.LastIndexOf("\u00ADn", position, position + 1)}"""

let position = s2.LastIndexOf "m"
printfn $"'m' at position {position}"

if position  >= 0 then
    printfn $"""{s2.LastIndexOf("\u00ADn", position, position + 1)}"""

// Find the index of the soft hyphen followed by "m".
let position = s1.LastIndexOf "m"
printfn $"'m' at position {position}"

if position  >= 0 then
    printfn $"""{s1.LastIndexOf("\u00ADm", position, position + 1)}"""

let position = s2.LastIndexOf "m"
printfn $"'m' at position {position}"

if position  >= 0 then
    printfn $"""{s2.LastIndexOf("\u00ADm", position, position + 1)}"""

// The example displays the following output:
//
// 'm' at position 4
// 1
// 'm' at position 3
// 1
// 'm' at position 4
// 4
// 'm' at position 3
// 3

Dim position As Integer
Dim softHyphen As String = ChrW(&HAD)

Dim s1 As String = "ani" + softHyphen + "mal"
Dim s2 As String = "animal"

' Find the index of the soft hyphen followed by "n".
position = s1.LastIndexOf("m")
Console.WriteLine($"'m' at position {position}")

If position >= 0 Then
    Console.WriteLine(s1.LastIndexOf(softHyphen + "n", position, position + 1))
End If

position = s2.LastIndexOf("m")
Console.WriteLine($"'m' at position {position}")

If position >= 0 Then
    Console.WriteLine(s2.LastIndexOf(softHyphen + "n", position, position + 1))
End If

' Find the index of the soft hyphen followed by "m".
position = s1.LastIndexOf("m")
Console.WriteLine($"'m' at position {position}")

If position >= 0 Then
    Console.WriteLine(s1.LastIndexOf(softHyphen + "m", position, position + 1))
End If

position = s2.LastIndexOf("m")
Console.WriteLine($"'m' at position {position}")

If position >= 0 Then
    Console.WriteLine(s2.LastIndexOf(softHyphen + "m", position, position + 1))
End If

' The example displays the following output:
'
' 'm' at position 4
' 1
' 'm' at position 3
' 1
' 'm' at position 4
' 4
' 'm' at position 3
' 3

Poznámky pro volající

Jak je vysvětleno v osvědčených postupů pro používání řetězců, doporučujeme vyhnout se volání metod porovnání řetězců, které nahrazují výchozí hodnoty a místo toho volají metody, které vyžadují explicitní zadání parametrů. Chcete-li provést tuto operaci pomocí srovnávacích pravidel aktuální jazykové verze, signalizovat záměr explicitně voláním přetížení metody LastIndexOf(String, Int32, Int32, StringComparison) s hodnotou CurrentCulture pro jeho comparisonType parametr. Pokud nepotřebujete porovnání s lingvistiky, zvažte použití Ordinal.

Viz také

• Int32
• IndexOf(Char)
• IndexOfAny(Char[])
• LastIndexOfAny(Char[])

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

public:
 int LastIndexOf(char value, int startIndex, int count);

public int LastIndexOf (char value, int startIndex, int count);

member this.LastIndexOf : char * int * int -> int

Public Function LastIndexOf (value As Char, startIndex As Integer, count As Integer) As Integer

Parametry

Návraty

Umístění indexu založeného na nule value, pokud je tento znak nalezen, nebo -1 pokud není nalezen nebo pokud aktuální instance se rovná Empty.

Výjimky

Příklady

Následující příklad najde index všech výskytů znaku v podřetězdci, který pracuje od konce podřetězdce až po začátek podřetězdce.

// Sample for String::LastIndexOf(Char, Int32, Int32)
using namespace System;
int main()
{
   String^ br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-";
   String^ br2 = "0123456789012345678901234567890123456789012345678901234567890123456";
   String^ str = "Now is the time for all good men to come to the aid of their party.";
   int start;
   int at;
   int count;
   int end;
   start = str->Length - 1;
   end = start / 2 - 1;
   Console::WriteLine( "All occurrences of 't' from position {0} to {1}.", start, end );
   Console::WriteLine( "\n{0}\n{1}\n{2}", br1, br2, str );
   Console::Write( "The letter 't' occurs at position(s): " );
   count = 0;
   at = 0;
   while ( (start > -1) && (at > -1) )
   {
      count = start - end; //Count must be within the substring.
      at = str->LastIndexOf( 't', start, count );
      if ( at > -1 )
      {
         Console::Write( " {0} ", at );
         start = at - 1;
      }
   }
}

/*
This example produces the following results:
All occurrences of 't' from position 66 to 32.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The letter 't' occurs at position(s): 64 55 44 41 33


*/

// Sample for String.LastIndexOf(Char, Int32, Int32)
using System;

class Sample {
    public static void Main() {

    string br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-";
    string br2 = "0123456789012345678901234567890123456789012345678901234567890123456";
    string str = "Now is the time for all good men to come to the aid of their party.";
    int start;
    int at;
    int count;
    int end;

    start = str.Length-1;
    end = start/2 - 1;
    Console.WriteLine("All occurrences of 't' from position {0} to {1}.", start, end);
    Console.WriteLine("{1}{0}{2}{0}{3}{0}", Environment.NewLine, br1, br2, str);
    Console.Write("The letter 't' occurs at position(s): ");

    count = 0;
    at = 0;
    while((start > -1) && (at > -1))
        {
        count = start - end; //Count must be within the substring.
        at = str.LastIndexOf('t', start, count);
        if (at > -1)
            {
            Console.Write("{0} ", at);
            start = at - 1;
            }
        }
    Console.Write("{0}{0}{0}", Environment.NewLine);
    }
}
/*
This example produces the following results:
All occurrences of 't' from position 66 to 32.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The letter 't' occurs at position(s): 64 55 44 41 33


*/

// Sample for String.LastIndexOf(Char, Int32, Int32)
open System

let br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-"
let br2 = "0123456789012345678901234567890123456789012345678901234567890123456"
let str = "Now is the time for all good men to come to the aid of their party."

let mutable start = str.Length-1
let last = start / 2 - 1
printfn $"All occurrences of 't' from position {start} to {last}."
printfn $"{br1}{Environment.NewLine}{br2}{Environment.NewLine}{str}{Environment.NewLine}"
printf "The letter 't' occurs at position(s): "

let mutable at = 0
while (start > -1) && (at > -1) do
    let count = start - last //Count must be within the substring.
    at <- str.LastIndexOf('t', start, count)
    if at > -1 then
        printf $"{at} "
        start <- at - 1
printf $"{Environment.NewLine}{Environment.NewLine}{Environment.NewLine}"
(*
This example produces the following results:
All occurrences of 't' from position 66 to 32.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The letter 't' occurs at position(s): 64 55 44 41 33


*)

' Sample for String.LastIndexOf(Char, Int32, Int32)
 _

Class Sample
   
   Public Shared Sub Main()
      
      Dim br1 As String = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-"
      Dim br2 As String = "0123456789012345678901234567890123456789012345678901234567890123456"
      Dim str As String = "Now is the time for all good men to come to the aid of their party."
      Dim start As Integer
      Dim at As Integer
      Dim count As Integer
      Dim [end] As Integer

      start = str.Length - 1
      [end] = start / 2 - 1
      Console.WriteLine("All occurrences of 't' from position {0} to {1}.", start, [end])
      Console.WriteLine("{1}{0}{2}{0}{3}{0}", Environment.NewLine, br1, br2, str)
      Console.Write("The letter 't' occurs at position(s): ")
      
      count = 0
      at = 0
      While start > - 1 And at > - 1
         count = start - [end] 'Count must be within the substring.
         at = str.LastIndexOf("t"c, start, count)
         If at > - 1 Then
            Console.Write("{0} ", at)
            start = at - 1
         End If
      End While
      Console.Write("{0}{0}{0}", Environment.NewLine)
   End Sub
End Class
'
'This example produces the following results:
'All occurrences of 't' from position 66 to 32.
'0----+----1----+----2----+----3----+----4----+----5----+----6----+-
'0123456789012345678901234567890123456789012345678901234567890123456
'Now is the time for all good men to come to the aid of their party.
'
'The letter 't' occurs at position(s): 64 55 44 41 33
'
'

Poznámky

Číslování indexů začíná od nuly. To znamená, že první znak v řetězci je na nule indexu a poslední je v Length - 1.

Tato metoda začne hledat na pozici znaku startIndex a pokračuje zpět směrem k začátku této instance, dokud se nenajde value nebo count pozice znaků byly prozkoumány. Pokud je například startIndexLength - 1, metoda vyhledá zpětně count znaky od posledního znaku v řetězci. Hledání se rozlišují malá a velká písmena.

Tato metoda provádí řadové vyhledávání (bez rozlišení jazykové verze), kde je znak považován za ekvivalentní jinému znaku pouze v případě, že skalární hodnota Unicode je stejná. Chcete-li provést vyhledávání citlivé na jazykovou verzi, použijte metodu CompareInfo.LastIndexOf, kde skalární hodnota Unicode představující předkomposovaný znak, například ligaturu "Æ" (U+00C6), může být v závislosti na jazykové verzi považována za ekvivalentní jakémukoli výskytu součástí znaku ve správném pořadí, například "AE" (U+0041, U+0045).

Viz také

• Char
• Int32
• IndexOf(Char)
• IndexOfAny(Char[])
• LastIndexOfAny(Char[])

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

public:
 int LastIndexOf(System::String ^ value, StringComparison comparisonType);

public int LastIndexOf (string value, StringComparison comparisonType);

member this.LastIndexOf : string * StringComparison -> int

Public Function LastIndexOf (value As String, comparisonType As StringComparison) As Integer

Parametry

Návraty

Pozice počátečního indexu založeného na nule parametru value, pokud se tento řetězec najde, nebo -1, pokud ne.

Výjimky

Příklady

Následující příklad ukazuje tři přetížení LastIndexOf metoda, které najdou poslední výskyt řetězce v jiném řetězci pomocí různých hodnot StringComparison výčtu.

// This code example demonstrates the 
// System.String.LastIndexOf(String, ..., StringComparison) methods.

using System;
using System.Threading;
using System.Globalization;

class Sample 
{
    public static void Main() 
    {
    string intro = "Find the last occurrence of a character using different " + 
                   "values of StringComparison.";
    string resultFmt = "Comparison: {0,-28} Location: {1,3}";

// Define a string to search for.
// U+00c5 = LATIN CAPITAL LETTER A WITH RING ABOVE
    string CapitalAWithRing = "\u00c5"; 

// Define a string to search. 
// The result of combining the characters LATIN SMALL LETTER A and COMBINING 
// RING ABOVE (U+0061, U+030a) is linguistically equivalent to the character 
// LATIN SMALL LETTER A WITH RING ABOVE (U+00e5).
    string cat = "A Cheshire c" + "\u0061\u030a" + "t";
    int loc = 0;
    StringComparison[] scValues = {
        StringComparison.CurrentCulture,
        StringComparison.CurrentCultureIgnoreCase,
        StringComparison.InvariantCulture,
        StringComparison.InvariantCultureIgnoreCase,
        StringComparison.Ordinal,
        StringComparison.OrdinalIgnoreCase };

// Clear the screen and display an introduction.
    Console.Clear();
    Console.WriteLine(intro);

// Display the current culture because culture affects the result. For example, 
// try this code example with the "sv-SE" (Swedish-Sweden) culture.

    Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");
    Console.WriteLine("The current culture is \"{0}\" - {1}.", 
                       Thread.CurrentThread.CurrentCulture.Name,
                       Thread.CurrentThread.CurrentCulture.DisplayName);

// Display the string to search for and the string to search.
    Console.WriteLine("Search for the string \"{0}\" in the string \"{1}\"", 
                       CapitalAWithRing, cat);
    Console.WriteLine();

// Note that in each of the following searches, we look for 
// LATIN CAPITAL LETTER A WITH RING ABOVE in a string that contains 
// LATIN SMALL LETTER A WITH RING ABOVE. A result value of -1 indicates 
// the string was not found.
// Search using different values of StringComparsion. Specify the start 
// index and count. 

    Console.WriteLine("Part 1: Start index and count are specified.");
    foreach (StringComparison sc in scValues)
        {
        loc = cat.LastIndexOf(CapitalAWithRing, cat.Length-1, cat.Length, sc);
        Console.WriteLine(resultFmt, sc, loc);
        }

// Search using different values of StringComparsion. Specify the 
// start index. 
    Console.WriteLine("\nPart 2: Start index is specified.");
    foreach (StringComparison sc in scValues)
        {
        loc = cat.LastIndexOf(CapitalAWithRing, cat.Length-1, sc);
        Console.WriteLine(resultFmt, sc, loc);
        }

// Search using different values of StringComparsion. 
    Console.WriteLine("\nPart 3: Neither start index nor count is specified.");
    foreach (StringComparison sc in scValues)
        {
        loc = cat.LastIndexOf(CapitalAWithRing, sc);
        Console.WriteLine(resultFmt, sc, loc);
        }
    }
}

/*
Note: This code example was executed on a console whose user interface 
culture is "en-US" (English-United States).

This code example produces the following results:

Find the last occurrence of a character using different values of StringComparison.
The current culture is "en-US" - English (United States).
Search for the string "Å" in the string "A Cheshire ca°t"

Part 1: Start index and count are specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

Part 2: Start index is specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

Part 3: Neither start index nor count is specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

*/

// This code example demonstrates the
// System.String.LastIndexOf(String, ..., StringComparison) methods.

open System
open System.Threading
open System.Globalization

let intro = "Find the last occurrence of a character using different values of StringComparison."

// Define a string to search for.
// U+00c5 = LATIN CAPITAL LETTER A WITH RING ABOVE
let CapitalAWithRing = "\u00c5"

// Define a string to search.
// The result of combining the characters LATIN SMALL LETTER A and COMBINING
// RING ABOVE (U+0061, U+030a) is linguistically equivalent to the character
// LATIN SMALL LETTER A WITH RING ABOVE (U+00e5).
let cat = "A Cheshire c" + "\u0061\u030a" + "t"
let loc = 0
let scValues = 
    [| StringComparison.CurrentCulture
       StringComparison.CurrentCultureIgnoreCase
       StringComparison.InvariantCulture
       StringComparison.InvariantCultureIgnoreCase
       StringComparison.Ordinal
       StringComparison.OrdinalIgnoreCase  |]

// Clear the screen and display an introduction.
Console.Clear()
printfn $"{intro}"

// Display the current culture because culture affects the result. For example,
// try this code example with the "sv-SE" (Swedish-Sweden) culture.

Thread.CurrentThread.CurrentCulture <- CultureInfo "en-US"
printfn $"The current culture is \"{Thread.CurrentThread.CurrentCulture.Name}\" - {Thread.CurrentThread.CurrentCulture.DisplayName}."

// Display the string to search for and the string to search.
printfn $"Search for the string \"{CapitalAWithRing}\" in the string \"{cat}\"\n"

// Note that in each of the following searches, we look for
// LATIN CAPITAL LETTER A WITH RING ABOVE in a string that contains
// LATIN SMALL LETTER A WITH RING ABOVE. A result value of -1 indicates
// the string was not found.
// Search using different values of StringComparsion. Specify the start
// index and count.

printfn "Part 1: Start index and count are specified."
for sc in scValues do
    let loc = cat.LastIndexOf(CapitalAWithRing, cat.Length-1, cat.Length, sc)
    printfn $"Comparison: {sc,-28} Location: {loc,3}"

// Search using different values of StringComparsion. Specify the
// start index.
printfn "\nPart 2: Start index is specified."
for sc in scValues do
    let loc = cat.LastIndexOf(CapitalAWithRing, cat.Length-1, sc)
    printfn $"Comparison: {sc,-28} Location: {loc,3}"

// Search using different values of StringComparsion.
printfn "\nPart 3: Neither start index nor count is specified."
for sc in scValues do
    let loc = cat.LastIndexOf(CapitalAWithRing, sc)
    printfn $"Comparison: {sc,-28} Location: {loc,3}"

(*
Note: This code example was executed on a console whose user interface
culture is "en-US" (English-United States).

This code example produces the following results:

Find the last occurrence of a character using different values of StringComparison.
The current culture is "en-US" - English (United States).
Search for the string "Å" in the string "A Cheshire ca°t"

Part 1: Start index and count are specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

Part 2: Start index is specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

Part 3: Neither start index nor count is specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

*)

' This code example demonstrates the 
' System.String.LastIndexOf(String, ..., StringComparison) methods.

Imports System.Threading
Imports System.Globalization

Class Sample
    Public Shared Sub Main() 
        Dim intro As String = "Find the last occurrence of a character using different " & _
                              "values of StringComparison."
        Dim resultFmt As String = "Comparison: {0,-28} Location: {1,3}"
        
        ' Define a string to search for.
        ' U+00c5 = LATIN CAPITAL LETTER A WITH RING ABOVE
        Dim CapitalAWithRing As String = "Å"
        
        ' Define a string to search. 
        ' The result of combining the characters LATIN SMALL LETTER A and COMBINING 
        ' RING ABOVE (U+0061, U+030a) is linguistically equivalent to the character 
        ' LATIN SMALL LETTER A WITH RING ABOVE (U+00e5).
        Dim cat As String = "A Cheshire c" & "å" & "t"
        Dim loc As Integer = 0
        Dim scValues As StringComparison() =  { _
                        StringComparison.CurrentCulture, _
                        StringComparison.CurrentCultureIgnoreCase, _
                        StringComparison.InvariantCulture, _
                        StringComparison.InvariantCultureIgnoreCase, _
                        StringComparison.Ordinal, _
                        StringComparison.OrdinalIgnoreCase }
        Dim sc As StringComparison
        
        ' Clear the screen and display an introduction.
        Console.Clear()
        Console.WriteLine(intro)
        
        ' Display the current culture because culture affects the result. For example, 
        ' try this code example with the "sv-SE" (Swedish-Sweden) culture.
        Thread.CurrentThread.CurrentCulture = New CultureInfo("en-US")
        Console.WriteLine("The current culture is ""{0}"" - {1}.", _
                           Thread.CurrentThread.CurrentCulture.Name, _
                           Thread.CurrentThread.CurrentCulture.DisplayName)
        
        ' Display the string to search for and the string to search.
        Console.WriteLine("Search for the string ""{0}"" in the string ""{1}""", _
                           CapitalAWithRing, cat)
        Console.WriteLine()
        
        ' Note that in each of the following searches, we look for 
        ' LATIN CAPITAL LETTER A WITH RING ABOVE in a string that contains 
        ' LATIN SMALL LETTER A WITH RING ABOVE. A result value of -1 indicates 
        ' the string was not found.
        ' Search using different values of StringComparsion. Specify the start 
        ' index and count. 
        Console.WriteLine("Part 1: Start index and count are specified.")
        For Each sc In  scValues
            loc = cat.LastIndexOf(CapitalAWithRing, cat.Length - 1, cat.Length, sc)
            Console.WriteLine(resultFmt, sc, loc)
        Next sc
        
        ' Search using different values of StringComparsion. Specify the 
        ' start index. 
        Console.WriteLine(vbCrLf & "Part 2: Start index is specified.")
        For Each sc In  scValues
            loc = cat.LastIndexOf(CapitalAWithRing, cat.Length - 1, sc)
            Console.WriteLine(resultFmt, sc, loc)
        Next sc
        
        ' Search using different values of StringComparsion. 
        Console.WriteLine(vbCrLf & "Part 3: Neither start index nor count is specified.")
        For Each sc In  scValues
            loc = cat.LastIndexOf(CapitalAWithRing, sc)
            Console.WriteLine(resultFmt, sc, loc)
        Next sc
    
    End Sub
End Class

'
'Note: This code example was executed on a console whose user interface 
'culture is "en-US" (English-United States).
'
'This code example produces the following results:
'
'Find the last occurrence of a character using different values of StringComparison.
'The current culture is "en-US" - English (United States).
'Search for the string "Å" in the string "A Cheshire ca°t"
'
'Part 1: Start index and count are specified.
'Comparison: CurrentCulture               Location:  -1
'Comparison: CurrentCultureIgnoreCase     Location:  12
'Comparison: InvariantCulture             Location:  -1
'Comparison: InvariantCultureIgnoreCase   Location:  12
'Comparison: Ordinal                      Location:  -1
'Comparison: OrdinalIgnoreCase            Location:  -1
'
'Part 2: Start index is specified.
'Comparison: CurrentCulture               Location:  -1
'Comparison: CurrentCultureIgnoreCase     Location:  12
'Comparison: InvariantCulture             Location:  -1
'Comparison: InvariantCultureIgnoreCase   Location:  12
'Comparison: Ordinal                      Location:  -1
'Comparison: OrdinalIgnoreCase            Location:  -1
'
'Part 3: Neither start index nor count is specified.
'Comparison: CurrentCulture               Location:  -1
'Comparison: CurrentCultureIgnoreCase     Location:  12
'Comparison: InvariantCulture             Location:  -1
'Comparison: InvariantCultureIgnoreCase   Location:  12
'Comparison: Ordinal                      Location:  -1
'Comparison: OrdinalIgnoreCase            Location:  -1
'

Poznámky

Číslování indexů začíná od nuly. To znamená, že první znak v řetězci je na nule indexu a poslední je v Length - 1.

Parametr comparisonType určuje, že se má vyhledat parametr value pomocí:

• Aktuální nebo invariantní jazyková verze.
• Vyhledávání nerozlišuje velká a malá a velká písmena.
• Pravidla porovnávání slov nebo řadových pravidel

Hledání začíná na poslední pozici znaku této instance a pokračuje zpět směrem k začátku, dokud se nenajde value nebo se prozkoumá první pozice znaku.

Poznámky pro volající

Znakové sady obsahují ignorovatelné znaky, což jsou znaky, které se při provádění jazykového nebo jazykového porovnání nerozlišují. V hledání citlivém na jazykovou verzi (to znamená, že pokud options není Ordinal nebo OrdinalIgnoreCase), pokud value obsahuje ignorovatelný znak, je výsledek ekvivalentní hledání s tímto znakem odebraným.

V následujícím příkladu se metoda LastIndexOf(String, StringComparison) používá k vyhledání dvou podřetězců (měkký spojovník následovaný "n" a měkký spojovník následovaný "m") ve dvou řetězcích. Pouze jeden z řetězců obsahuje měkké pomlčky. Pokud je příklad spuštěn v rozhraní .NET Framework 4 nebo novější, protože měkký spojovník je ignorovatelný znak, vrátí vyhledávání citlivé na jazykovou verzi stejnou hodnotu, kterou by vrátila, pokud by se do vyhledávacího řetězce nezahrnulo měkké pomlčky. Pořadové vyhledávání však úspěšně najde měkké spojovníky v jednom řetězci a hlásí, že chybí ve druhém řetězci.

string s1 = "ani\u00ADmal";
string s2 = "animal";

Console.WriteLine("Culture-sensitive comparison:");

// Use culture-sensitive comparison to find the last soft hyphen followed by "n".
Console.WriteLine(s1.LastIndexOf("\u00ADn", StringComparison.CurrentCulture));
Console.WriteLine(s2.LastIndexOf("\u00ADn", StringComparison.CurrentCulture));

// Use culture-sensitive comparison to find the last soft hyphen followed by "m".
Console.WriteLine(s1.LastIndexOf("\u00ADm", StringComparison.CurrentCulture));
Console.WriteLine(s2.LastIndexOf("\u00ADm", StringComparison.CurrentCulture));

Console.WriteLine("Ordinal comparison:");

// Use ordinal comparison to find the last soft hyphen followed by "n".
Console.WriteLine(s1.LastIndexOf("\u00ADn", StringComparison.Ordinal));
Console.WriteLine(s2.LastIndexOf("\u00ADn", StringComparison.Ordinal));

// Use ordinal comparison to find the last soft hyphen followed by "m".
Console.WriteLine(s1.LastIndexOf("\u00ADm", StringComparison.Ordinal));
Console.WriteLine(s2.LastIndexOf("\u00ADm", StringComparison.Ordinal));

// The example displays the following output:
//
// Culture-sensitive comparison:
// 1
// 1
// 4
// 3
// Ordinal comparison:
// -1
// -1
// 3
// -1

open System

let s1 = "ani\u00ADmal"
let s2 = "animal"

printfn "Culture-sensitive comparison:"

// Use culture-sensitive comparison to find the last soft hyphen followed by "n".
printfn $"""{s1.LastIndexOf("\u00ADn", StringComparison.CurrentCulture)}"""
printfn $"""{s2.LastIndexOf("\u00ADn", StringComparison.CurrentCulture)}"""

// Use culture-sensitive comparison to find the last soft hyphen followed by "m".
printfn $"""{s1.LastIndexOf("\u00ADm", StringComparison.CurrentCulture)}"""
printfn $"""{s2.LastIndexOf("\u00ADm", StringComparison.CurrentCulture)}"""

printfn "Ordinal comparison:"

// Use ordinal comparison to find the last soft hyphen followed by "n".
printfn $"""{s1.LastIndexOf("\u00ADn", StringComparison.Ordinal)}"""
printfn $"""{s2.LastIndexOf("\u00ADn", StringComparison.Ordinal)}"""

// Use ordinal comparison to find the last soft hyphen followed by "m".
printfn $"""{s1.LastIndexOf("\u00ADm", StringComparison.Ordinal)}"""
printfn $"""{s2.LastIndexOf("\u00ADm", StringComparison.Ordinal)}"""

// The example displays the following output:
//
// Culture-sensitive comparison:
// 1
// 1
// 4
// 3
// Ordinal comparison:
// -1
// -1
// 3
// -1

Dim softHyphen As String = ChrW(&HAD)
Dim s1 As String = "ani" + softHyphen + "mal"
Dim s2 As String = "animal"

Console.WriteLine("Culture-sensitive comparison:")

' Use culture-sensitive comparison to find the last soft hyphen followed by "n".
Console.WriteLine(s1.LastIndexOf(softHyphen + "n", StringComparison.CurrentCulture))
Console.WriteLine(s2.LastIndexOf(softHyphen + "n", StringComparison.CurrentCulture))

' Use culture-sensitive comparison to find the last soft hyphen followed by "m".
Console.WriteLine(s1.LastIndexOf(softHyphen + "m", StringComparison.CurrentCulture))
Console.WriteLine(s2.LastIndexOf(softHyphen + "m", StringComparison.CurrentCulture))

Console.WriteLine("Ordinal comparison:")

' Use ordinal comparison to find the last soft hyphen followed by "n".
Console.WriteLine(s1.LastIndexOf(softHyphen + "n", StringComparison.Ordinal))
Console.WriteLine(s2.LastIndexOf(softHyphen + "n", StringComparison.Ordinal))

' Use ordinal comparison to find the last soft hyphen followed by "m".
Console.WriteLine(s1.LastIndexOf(softHyphen + "m", StringComparison.Ordinal))
Console.WriteLine(s2.LastIndexOf(softHyphen + "m", StringComparison.Ordinal))

' The example displays the following output:
'
' Culture-sensitive comparison:
' 1
' 1
' 4
' 3
' Ordinal comparison:
' -1
' -1
' 3
' -1

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

public:
 int LastIndexOf(System::String ^ value, int startIndex, StringComparison comparisonType);

public int LastIndexOf (string value, int startIndex, StringComparison comparisonType);

member this.LastIndexOf : string * int * StringComparison -> int

Public Function LastIndexOf (value As String, startIndex As Integer, comparisonType As StringComparison) As Integer

Parametry

Návraty

Pozice počátečního indexu založeného na nule value parametru, pokud je tento řetězec nalezen, nebo -1 pokud není nalezena nebo pokud aktuální instance se rovná Empty.

Výjimky

Příklady

Následující příklad ukazuje tři přetížení LastIndexOf metoda, které najdou poslední výskyt řetězce v jiném řetězci pomocí různých hodnot StringComparison výčtu.

// This code example demonstrates the 
// System.String.LastIndexOf(String, ..., StringComparison) methods.

using System;
using System.Threading;
using System.Globalization;

class Sample 
{
    public static void Main() 
    {
    string intro = "Find the last occurrence of a character using different " + 
                   "values of StringComparison.";
    string resultFmt = "Comparison: {0,-28} Location: {1,3}";

// Define a string to search for.
// U+00c5 = LATIN CAPITAL LETTER A WITH RING ABOVE
    string CapitalAWithRing = "\u00c5"; 

// Define a string to search. 
// The result of combining the characters LATIN SMALL LETTER A and COMBINING 
// RING ABOVE (U+0061, U+030a) is linguistically equivalent to the character 
// LATIN SMALL LETTER A WITH RING ABOVE (U+00e5).
    string cat = "A Cheshire c" + "\u0061\u030a" + "t";
    int loc = 0;
    StringComparison[] scValues = {
        StringComparison.CurrentCulture,
        StringComparison.CurrentCultureIgnoreCase,
        StringComparison.InvariantCulture,
        StringComparison.InvariantCultureIgnoreCase,
        StringComparison.Ordinal,
        StringComparison.OrdinalIgnoreCase };

// Clear the screen and display an introduction.
    Console.Clear();
    Console.WriteLine(intro);

// Display the current culture because culture affects the result. For example, 
// try this code example with the "sv-SE" (Swedish-Sweden) culture.

    Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");
    Console.WriteLine("The current culture is \"{0}\" - {1}.", 
                       Thread.CurrentThread.CurrentCulture.Name,
                       Thread.CurrentThread.CurrentCulture.DisplayName);

// Display the string to search for and the string to search.
    Console.WriteLine("Search for the string \"{0}\" in the string \"{1}\"", 
                       CapitalAWithRing, cat);
    Console.WriteLine();

// Note that in each of the following searches, we look for 
// LATIN CAPITAL LETTER A WITH RING ABOVE in a string that contains 
// LATIN SMALL LETTER A WITH RING ABOVE. A result value of -1 indicates 
// the string was not found.
// Search using different values of StringComparsion. Specify the start 
// index and count. 

    Console.WriteLine("Part 1: Start index and count are specified.");
    foreach (StringComparison sc in scValues)
        {
        loc = cat.LastIndexOf(CapitalAWithRing, cat.Length-1, cat.Length, sc);
        Console.WriteLine(resultFmt, sc, loc);
        }

// Search using different values of StringComparsion. Specify the 
// start index. 
    Console.WriteLine("\nPart 2: Start index is specified.");
    foreach (StringComparison sc in scValues)
        {
        loc = cat.LastIndexOf(CapitalAWithRing, cat.Length-1, sc);
        Console.WriteLine(resultFmt, sc, loc);
        }

// Search using different values of StringComparsion. 
    Console.WriteLine("\nPart 3: Neither start index nor count is specified.");
    foreach (StringComparison sc in scValues)
        {
        loc = cat.LastIndexOf(CapitalAWithRing, sc);
        Console.WriteLine(resultFmt, sc, loc);
        }
    }
}

/*
Note: This code example was executed on a console whose user interface 
culture is "en-US" (English-United States).

This code example produces the following results:

Find the last occurrence of a character using different values of StringComparison.
The current culture is "en-US" - English (United States).
Search for the string "Å" in the string "A Cheshire ca°t"

Part 1: Start index and count are specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

Part 2: Start index is specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

Part 3: Neither start index nor count is specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

*/

// This code example demonstrates the
// System.String.LastIndexOf(String, ..., StringComparison) methods.

open System
open System.Threading
open System.Globalization

let intro = "Find the last occurrence of a character using different values of StringComparison."

// Define a string to search for.
// U+00c5 = LATIN CAPITAL LETTER A WITH RING ABOVE
let CapitalAWithRing = "\u00c5"

// Define a string to search.
// The result of combining the characters LATIN SMALL LETTER A and COMBINING
// RING ABOVE (U+0061, U+030a) is linguistically equivalent to the character
// LATIN SMALL LETTER A WITH RING ABOVE (U+00e5).
let cat = "A Cheshire c" + "\u0061\u030a" + "t"
let loc = 0
let scValues = 
    [| StringComparison.CurrentCulture
       StringComparison.CurrentCultureIgnoreCase
       StringComparison.InvariantCulture
       StringComparison.InvariantCultureIgnoreCase
       StringComparison.Ordinal
       StringComparison.OrdinalIgnoreCase  |]

// Clear the screen and display an introduction.
Console.Clear()
printfn $"{intro}"

// Display the current culture because culture affects the result. For example,
// try this code example with the "sv-SE" (Swedish-Sweden) culture.

Thread.CurrentThread.CurrentCulture <- CultureInfo "en-US"
printfn $"The current culture is \"{Thread.CurrentThread.CurrentCulture.Name}\" - {Thread.CurrentThread.CurrentCulture.DisplayName}."

// Display the string to search for and the string to search.
printfn $"Search for the string \"{CapitalAWithRing}\" in the string \"{cat}\"\n"

// Note that in each of the following searches, we look for
// LATIN CAPITAL LETTER A WITH RING ABOVE in a string that contains
// LATIN SMALL LETTER A WITH RING ABOVE. A result value of -1 indicates
// the string was not found.
// Search using different values of StringComparsion. Specify the start
// index and count.

printfn "Part 1: Start index and count are specified."
for sc in scValues do
    let loc = cat.LastIndexOf(CapitalAWithRing, cat.Length-1, cat.Length, sc)
    printfn $"Comparison: {sc,-28} Location: {loc,3}"

// Search using different values of StringComparsion. Specify the
// start index.
printfn "\nPart 2: Start index is specified."
for sc in scValues do
    let loc = cat.LastIndexOf(CapitalAWithRing, cat.Length-1, sc)
    printfn $"Comparison: {sc,-28} Location: {loc,3}"

// Search using different values of StringComparsion.
printfn "\nPart 3: Neither start index nor count is specified."
for sc in scValues do
    let loc = cat.LastIndexOf(CapitalAWithRing, sc)
    printfn $"Comparison: {sc,-28} Location: {loc,3}"

(*
Note: This code example was executed on a console whose user interface
culture is "en-US" (English-United States).

This code example produces the following results:

Find the last occurrence of a character using different values of StringComparison.
The current culture is "en-US" - English (United States).
Search for the string "Å" in the string "A Cheshire ca°t"

Part 1: Start index and count are specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

Part 2: Start index is specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

Part 3: Neither start index nor count is specified.
Comparison: CurrentCulture               Location:  -1
Comparison: CurrentCultureIgnoreCase     Location:  12
Comparison: InvariantCulture             Location:  -1
Comparison: InvariantCultureIgnoreCase   Location:  12
Comparison: Ordinal                      Location:  -1
Comparison: OrdinalIgnoreCase            Location:  -1

*)

' This code example demonstrates the 
' System.String.LastIndexOf(String, ..., StringComparison) methods.

Imports System.Threading
Imports System.Globalization

Class Sample
    Public Shared Sub Main() 
        Dim intro As String = "Find the last occurrence of a character using different " & _
                              "values of StringComparison."
        Dim resultFmt As String = "Comparison: {0,-28} Location: {1,3}"
        
        ' Define a string to search for.
        ' U+00c5 = LATIN CAPITAL LETTER A WITH RING ABOVE
        Dim CapitalAWithRing As String = "Å"
        
        ' Define a string to search. 
        ' The result of combining the characters LATIN SMALL LETTER A and COMBINING 
        ' RING ABOVE (U+0061, U+030a) is linguistically equivalent to the character 
        ' LATIN SMALL LETTER A WITH RING ABOVE (U+00e5).
        Dim cat As String = "A Cheshire c" & "å" & "t"
        Dim loc As Integer = 0
        Dim scValues As StringComparison() =  { _
                        StringComparison.CurrentCulture, _
                        StringComparison.CurrentCultureIgnoreCase, _
                        StringComparison.InvariantCulture, _
                        StringComparison.InvariantCultureIgnoreCase, _
                        StringComparison.Ordinal, _
                        StringComparison.OrdinalIgnoreCase }
        Dim sc As StringComparison
        
        ' Clear the screen and display an introduction.
        Console.Clear()
        Console.WriteLine(intro)
        
        ' Display the current culture because culture affects the result. For example, 
        ' try this code example with the "sv-SE" (Swedish-Sweden) culture.
        Thread.CurrentThread.CurrentCulture = New CultureInfo("en-US")
        Console.WriteLine("The current culture is ""{0}"" - {1}.", _
                           Thread.CurrentThread.CurrentCulture.Name, _
                           Thread.CurrentThread.CurrentCulture.DisplayName)
        
        ' Display the string to search for and the string to search.
        Console.WriteLine("Search for the string ""{0}"" in the string ""{1}""", _
                           CapitalAWithRing, cat)
        Console.WriteLine()
        
        ' Note that in each of the following searches, we look for 
        ' LATIN CAPITAL LETTER A WITH RING ABOVE in a string that contains 
        ' LATIN SMALL LETTER A WITH RING ABOVE. A result value of -1 indicates 
        ' the string was not found.
        ' Search using different values of StringComparsion. Specify the start 
        ' index and count. 
        Console.WriteLine("Part 1: Start index and count are specified.")
        For Each sc In  scValues
            loc = cat.LastIndexOf(CapitalAWithRing, cat.Length - 1, cat.Length, sc)
            Console.WriteLine(resultFmt, sc, loc)
        Next sc
        
        ' Search using different values of StringComparsion. Specify the 
        ' start index. 
        Console.WriteLine(vbCrLf & "Part 2: Start index is specified.")
        For Each sc In  scValues
            loc = cat.LastIndexOf(CapitalAWithRing, cat.Length - 1, sc)
            Console.WriteLine(resultFmt, sc, loc)
        Next sc
        
        ' Search using different values of StringComparsion. 
        Console.WriteLine(vbCrLf & "Part 3: Neither start index nor count is specified.")
        For Each sc In  scValues
            loc = cat.LastIndexOf(CapitalAWithRing, sc)
            Console.WriteLine(resultFmt, sc, loc)
        Next sc
    
    End Sub
End Class

'
'Note: This code example was executed on a console whose user interface 
'culture is "en-US" (English-United States).
'
'This code example produces the following results:
'
'Find the last occurrence of a character using different values of StringComparison.
'The current culture is "en-US" - English (United States).
'Search for the string "Å" in the string "A Cheshire ca°t"
'
'Part 1: Start index and count are specified.
'Comparison: CurrentCulture               Location:  -1
'Comparison: CurrentCultureIgnoreCase     Location:  12
'Comparison: InvariantCulture             Location:  -1
'Comparison: InvariantCultureIgnoreCase   Location:  12
'Comparison: Ordinal                      Location:  -1
'Comparison: OrdinalIgnoreCase            Location:  -1
'
'Part 2: Start index is specified.
'Comparison: CurrentCulture               Location:  -1
'Comparison: CurrentCultureIgnoreCase     Location:  12
'Comparison: InvariantCulture             Location:  -1
'Comparison: InvariantCultureIgnoreCase   Location:  12
'Comparison: Ordinal                      Location:  -1
'Comparison: OrdinalIgnoreCase            Location:  -1
'
'Part 3: Neither start index nor count is specified.
'Comparison: CurrentCulture               Location:  -1
'Comparison: CurrentCultureIgnoreCase     Location:  12
'Comparison: InvariantCulture             Location:  -1
'Comparison: InvariantCultureIgnoreCase   Location:  12
'Comparison: Ordinal                      Location:  -1
'Comparison: OrdinalIgnoreCase            Location:  -1
'

Poznámky

Číslování indexů začíná od nuly. To znamená, že první znak v řetězci je na nule indexu a poslední je v Length - 1.

Hledání začíná na pozici startIndex znaku a pokračuje zpět, dokud se nenajde value nebo se prozkoumá první pozice znaku. Pokud je například startIndexLength - 1, metoda vyhledá každý znak od posledního znaku v řetězci na začátek.

Parametr comparisonType určuje, že má hledat parametr value pomocí aktuální nebo invariantní jazykové verze, pomocí vyhledávání bez rozlišování velkých a malých a velkých písmen a použití pravidel porovnání slov nebo řadových porovnání.

Poznámky pro volající

Znakové sady obsahují ignorovatelné znaky, což jsou znaky, které se při provádění jazykového nebo jazykového porovnání nerozlišují. V hledání citlivém na jazykovou verzi (to znamená, že pokud comparisonType není Ordinal nebo OrdinalIgnoreCase), pokud value obsahuje ignorovatelný znak, je výsledek ekvivalentní hledání s tímto znakem odebraným.

V následujícím příkladu se metoda LastIndexOf(String, Int32, StringComparison) používá k vyhledání pozice měkkého spojovníku (U+00AD), za kterým následuje "m", počínaje posledním "m" ve dvou řetězcích. Požadovaný podřetězc obsahuje pouze jeden z řetězců. Pokud je příklad spuštěn v rozhraní .NET Framework 4 nebo novější, v obou případech, protože měkký spojovník je ignorovatelný znak, metoda vrátí index "m" v řetězci, když provede porovnání s jazykovou verzí. Všimněte si, že v případě prvního řetězce, který obsahuje měkké pomlčky následované znakem "m", metoda vrátí index "m" a ne index měkkého spojovníku. Metoda vrátí index měkkého spojovníku v prvním řetězci pouze při provádění pořadového porovnání.

string searchString = "\u00ADm";

string s1 = "ani\u00ADmal";
string s2 = "animal";

int position;

position = s1.LastIndexOf('m');
if (position >= 0)
{
    Console.WriteLine(s1.LastIndexOf(searchString, position, StringComparison.CurrentCulture));
    Console.WriteLine(s1.LastIndexOf(searchString, position, StringComparison.Ordinal));
}

position = s2.LastIndexOf('m');
if (position >= 0)
{
    Console.WriteLine(s2.LastIndexOf(searchString, position, StringComparison.CurrentCulture));
    Console.WriteLine(s2.LastIndexOf(searchString, position, StringComparison.Ordinal));
}

// The example displays the following output:
//
// 4
// 3
// 3
// -1

    let searchString = "\u00ADm"

    let s1 = "ani\u00ADmal"
    let s2 = "animal"

    let position = s1.LastIndexOf 'm'
    if position >= 0 then
        printfn $"{s1.LastIndexOf(searchString, position, StringComparison.CurrentCulture)}"
        printfn $"{s1.LastIndexOf(searchString, position, StringComparison.Ordinal)}"

    let position = s2.LastIndexOf 'm'
    if position >= 0 then
        printfn $"{s2.LastIndexOf(searchString, position, StringComparison.CurrentCulture)}"
        printfn $"{s2.LastIndexOf(searchString, position, StringComparison.Ordinal)}"

// The example displays the following output:
//
// 4
// 3
// 3
// -1

Dim searchString As String = ChrW(&HAD) + "m"

Dim s1 As String = "ani" + ChrW(&HAD) + "mal"
Dim s2 As String = "animal"

Dim position As Integer

position = s1.LastIndexOf("m"c)
If position >= 0 Then
    Console.WriteLine(s1.LastIndexOf(searchString, position, StringComparison.CurrentCulture))
    Console.WriteLine(s1.LastIndexOf(searchString, position, StringComparison.Ordinal))
End If

position = s2.LastIndexOf("m"c)
If position >= 0 Then
    Console.WriteLine(s2.LastIndexOf(searchString, position, StringComparison.CurrentCulture))
    Console.WriteLine(s2.LastIndexOf(searchString, position, StringComparison.Ordinal))
End If

' The example displays the following output:
'
' 4
' 3
' 3
' -1

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

public:
 int LastIndexOf(char value, int startIndex);

public int LastIndexOf (char value, int startIndex);

member this.LastIndexOf : char * int -> int

Public Function LastIndexOf (value As Char, startIndex As Integer) As Integer

Parametry

Návraty

Umístění indexu založeného na nule value, pokud je tento znak nalezen, nebo -1 pokud není nalezen nebo pokud aktuální instance se rovná Empty.

Výjimky

Příklady

Následující příklad najde index všech výskytů znaku v řetězci, který pracuje od konce řetězce po začátek řetězce.

// Sample for String::LastIndexOf(Char, Int32)
using namespace System;
int main()
{
   String^ br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-";
   String^ br2 = "0123456789012345678901234567890123456789012345678901234567890123456";
   String^ str = "Now is the time for all good men to come to the aid of their party.";
   int start;
   int at;
   start = str->Length - 1;
   Console::WriteLine( "All occurrences of 't' from position {0} to 0.", start );
   Console::WriteLine( "{0}\n{1}\n{2}\n", br1, br2, str );
   Console::Write( "The letter 't' occurs at position(s): " );
   at = 0;
   while ( (start > -1) && (at > -1) )
   {
      at = str->LastIndexOf( 't', start );
      if ( at > -1 )
      {
         Console::Write( " {0} ", at );
         start = at - 1;
      }
   }
}

/*
This example produces the following results:
All occurrences of 't' from position 66 to 0.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The letter 't' occurs at position(s): 64 55 44 41 33 11 7
*/

// Sample for String.LastIndexOf(Char, Int32)
using System;

class Sample {
    public static void Main() {

    string br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-";
    string br2 = "0123456789012345678901234567890123456789012345678901234567890123456";
    string str = "Now is the time for all good men to come to the aid of their party.";
    int start;
    int at;

    start = str.Length-1;
    Console.WriteLine("All occurrences of 't' from position {0} to 0.", start);
    Console.WriteLine("{1}{0}{2}{0}{3}{0}", Environment.NewLine, br1, br2, str);
    Console.Write("The letter 't' occurs at position(s): ");

    at = 0;
    while((start > -1) && (at > -1))
        {
        at = str.LastIndexOf('t', start);
        if (at > -1)
            {
            Console.Write("{0} ", at);
            start = at - 1;
            }
        }
    Console.Write("{0}{0}{0}", Environment.NewLine);
    }
}
/*
This example produces the following results:
All occurrences of 't' from position 66 to 0.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The letter 't' occurs at position(s): 64 55 44 41 33 11 7
*/

// Sample for String.LastIndexOf(Char, Int32)
open System

let br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-"
let br2 = "0123456789012345678901234567890123456789012345678901234567890123456"
let str = "Now is the time for all good men to come to the aid of their party."

let mutable start = str.Length - 1
printfn $"All occurrences of 't' from position {start} to 0."
printfn $"{br1}{Environment.NewLine}{br2}{Environment.NewLine}{str}{Environment.NewLine}"
printf "The letter 't' occurs at position(s): "

let mutable at = 0
while (start > -1) && (at > -1) do
    at <- str.LastIndexOf('t', start)
    if at > -1 then
        printf $"{at} "
        start <- at - 1
printf $"{Environment.NewLine}{Environment.NewLine}{Environment.NewLine}"
(*
This example produces the following results:
All occurrences of 't' from position 66 to 0.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The letter 't' occurs at position(s): 64 55 44 41 33 11 7
*)

' Sample for String.LastIndexOf(Char, Int32)
Imports System 
 _

Class Sample
   
   Public Shared Sub Main()
      
      Dim br1 As String = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-"
      Dim br2 As String = "0123456789012345678901234567890123456789012345678901234567890123456"
      Dim str As String = "Now is the time for all good men to come to the aid of their party."
      Dim start As Integer
      Dim at As Integer
      
      start = str.Length - 1
      Console.WriteLine("All occurrences of 't' from position {0} to 0.", start)
      Console.WriteLine("{1}{0}{2}{0}{3}{0}", Environment.NewLine, br1, br2, str)
      Console.Write("The letter 't' occurs at position(s): ")
      
      at = 0
      While start > - 1 And at > - 1
         at = str.LastIndexOf("t"c, start)
         If at > - 1 Then
            Console.Write("{0} ", at)
            start = at - 1
         End If
      End While
      Console.Write("{0}{0}{0}", Environment.NewLine)
   End Sub
End Class
'
'This example produces the following results:
'All occurrences of 't' from position 66 to 0.
'0----+----1----+----2----+----3----+----4----+----5----+----6----+-
'0123456789012345678901234567890123456789012345678901234567890123456
'Now is the time for all good men to come to the aid of their party.
'
'The letter 't' occurs at position(s): 64 55 44 41 33 11 7
'

Poznámky

Číslování indexů začíná od nuly. To znamená, že první znak v řetězci je na nule indexu a poslední je v Length - 1. Tato metoda začne prohledávat startIndex pozici znaku této instance a pokračuje zpět k začátku aktuální instance, dokud se nenajde value nebo se prozkoumá první pozice znaku. Pokud je například startIndexLength - 1, metoda vyhledá každý znak od posledního znaku v řetězci na začátek. Hledání se rozlišují malá a velká písmena.

Tato metoda provádí řadové vyhledávání (bez rozlišení jazykové verze), kde se znak považuje za ekvivalentní jinému znaku pouze v případě, že skalární hodnoty Unicode jsou stejné. Chcete-li provést vyhledávání citlivé na jazykovou verzi, použijte metodu CompareInfo.LastIndexOf, kde skalární hodnota Unicode představující předkomposovaný znak, například ligaturu "Æ" (U+00C6), může být v závislosti na jazykové verzi považována za ekvivalentní jakémukoli výskytu součástí znaku ve správném pořadí, například "AE" (U+0041, U+0045).

Viz také

• Char
• Int32
• IndexOf(Char)
• IndexOfAny(Char[])
• LastIndexOfAny(Char[])

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

public:
 int LastIndexOf(System::String ^ value);

public int LastIndexOf (string value);

member this.LastIndexOf : string -> int

Public Function LastIndexOf (value As String) As Integer

Parametry

Návraty

Pozice počátečního indexu založeného na nule value, pokud se tento řetězec najde, nebo -1, pokud není.

Výjimky

Příklady

Následující příklad odebere otevírání a zavírání značek HTML z řetězce, pokud značky začínají a ukončují řetězec. Pokud řetězec končí znakem uzavírací hranaté závorky (">"), příklad používá metodu LastIndexOf k vyhledání začátku koncové značky.

using System;

public class Example 
{
   public static void Main() 
   {
      string[] strSource = { "<b>This is bold text</b>", "<H1>This is large Text</H1>",
               "<b><i><font color=green>This has multiple tags</font></i></b>",
               "<b>This has <i>embedded</i> tags.</b>",
               "This line ends with a greater than symbol and should not be modified>" };

      // Strip HTML start and end tags from each string if they are present.
      foreach (string s in strSource)
      {
         Console.WriteLine("Before: " + s);
         string item = s;
         // Use EndsWith to find a tag at the end of the line.
         if (item.Trim().EndsWith(">")) 
         {
            // Locate the opening tag.
            int endTagStartPosition = item.LastIndexOf("</");
            // Remove the identified section, if it is valid.
            if (endTagStartPosition >= 0 )
               item = item.Substring(0, endTagStartPosition);

            // Use StartsWith to find the opening tag.
            if (item.Trim().StartsWith("<"))
            {
               // Locate the end of opening tab.
               int openTagEndPosition = item.IndexOf(">");
               // Remove the identified section, if it is valid.
               if (openTagEndPosition >= 0)
                  item = item.Substring(openTagEndPosition + 1);
            }      
         }
         // Display the trimmed string.
         Console.WriteLine("After: " + item);
         Console.WriteLine();
      }                   
   }
}
// The example displays the following output:
//    Before: <b>This is bold text</b>
//    After: This is bold text
//    
//    Before: <H1>This is large Text</H1>
//    After: This is large Text
//    
//    Before: <b><i><font color=green>This has multiple tags</font></i></b>
//    After: <i><font color=green>This has multiple tags</font></i>
//    
//    Before: <b>This has <i>embedded</i> tags.</b>
//    After: This has <i>embedded</i> tags.
//    
//    Before: This line ends with a greater than symbol and should not be modified>
//    After: This line ends with a greater than symbol and should not be modified>

let strSource = 
    [| "<b>This is bold text</b>"; "<H1>This is large Text</H1>"
       "<b><i><font color=green>This has multiple tags</font></i></b>"
       "<b>This has <i>embedded</i> tags.</b>"
       "This line ends with a greater than symbol and should not be modified>" |]

// Strip HTML start and end tags from each string if they are present.
for s in strSource do
    printfn $"Before: {s}"
    let mutable item = s
    // Use EndsWith to find a tag at the end of the line.
    if item.Trim().EndsWith ">" then
        // Locate the opening tag.
        let endTagStartPosition = item.LastIndexOf "</"
        // Remove the identified section, if it is valid.
        if endTagStartPosition >= 0 then
            item <- item.Substring(0, endTagStartPosition)

        // Use StartsWith to find the opening tag.
        if item.Trim().StartsWith "<" then
            // Locate the end of opening tab.
            let openTagEndPosition = item.IndexOf ">"
            // Remove the identified section, if it is valid.
            if openTagEndPosition >= 0 then
                item <- item.Substring(openTagEndPosition + 1)
    // Display the trimmed string.
    printfn "After: {item}"
    printfn ""
// The example displays the following output:
//    Before: <b>This is bold text</b>
//    After: This is bold text
//
//    Before: <H1>This is large Text</H1>
//    After: This is large Text
//
//    Before: <b><i><font color=green>This has multiple tags</font></i></b>
//    After: <i><font color=green>This has multiple tags</font></i>
//
//    Before: <b>This has <i>embedded</i> tags.</b>
//    After: This has <i>embedded</i> tags.
//
//    Before: This line ends with a greater than symbol and should not be modified>
//    After: This line ends with a greater than symbol and should not be modified>

Module Example
   Public Sub Main()
      Dim strSource As String() = { "<b>This is bold text</b>", _
                    "<H1>This is large Text</H1>", _
                    "<b><i><font color=green>This has multiple tags</font></i></b>", _
                    "<b>This has <i>embedded</i> tags.</b>", _
                    "This line ends with a greater than symbol and should not be modified>" }

      ' Strip HTML start and end tags from each string if they are present.
      For Each s As String In strSource
         Console.WriteLine("Before: " + s)
         ' Use EndsWith to find a tag at the end of the line.
         If s.Trim().EndsWith(">") Then 
            ' Locate the opening tag.
            Dim endTagStartPosition As Integer = s.LastIndexOf("</")
            ' Remove the identified section if it is valid.
            If endTagStartPosition >= 0 Then
               s = s.Substring(0, endTagStartPosition)
            End If
            
            ' Use StartsWith to find the opening tag.
            If s.Trim().StartsWith("<") Then
               ' Locate the end of opening tab.
               Dim openTagEndPosition As Integer = s.IndexOf(">")
               ' Remove the identified section if it is valid.
               If openTagEndPosition >= 0 Then
                  s = s.Substring(openTagEndPosition + 1)
               End If   
            End If      
         End If
         ' Display the trimmed string.
         Console.WriteLine("After: " + s)
         Console.WriteLine()
      Next                   
   End Sub
End Module
' The example displays the following output:
'    Before: <b>This is bold text</b>
'    After: This is bold text
'    
'    Before: <H1>This is large Text</H1>
'    After: This is large Text
'    
'    Before: <b><i><font color=green>This has multiple tags</font></i></b>
'    After: <i><font color=green>This has multiple tags</font></i>
'    
'    Before: <b>This has <i>embedded</i> tags.</b>
'    After: This has <i>embedded</i> tags.
'    
'    Before: This line ends with a greater than symbol and should not be modified>
'    After: This line ends with a greater than symbol and should not be modified>

Poznámky

Číslování indexů začíná od nuly. To znamená, že první znak v řetězci je na nule indexu a poslední je v Length - 1.

Hledání začíná na poslední pozici znaku této instance a pokračuje zpět směrem k začátku, dokud se nenajde value nebo se prozkoumá první pozice znaku.

Tato metoda provádí hledání slov (rozlišujících velká a malá písmena a jazykové verze) pomocí aktuální jazykové verze.

Znakové sady obsahují ignorovatelné znaky, což jsou znaky, které se při provádění jazykového nebo jazykového porovnání nerozlišují. Pokud v hledání citlivém na jazykovou verzi value obsahuje ignorovatelný znak, výsledek odpovídá hledání s odebraným znakem.

V následujícím příkladu se metoda LastIndexOf(String) používá k vyhledání dvou podřetězců (měkký spojovník následovaný "n" a měkký spojovník následovaný "m") ve dvou řetězcích. Pouze jeden z řetězců obsahuje měkké pomlčky. Pokud je příklad spuštěn v rozhraní .NET Framework 4 nebo novější, v každém případě, protože měkký spojovník je ignorovatelný znak, výsledek je stejný jako v případě, že měkké pomlčky nebyly zahrnuty do value.

string s1 = "ani\u00ADmal";
string s2 = "animal";

// Find the index of the last soft hyphen followed by "n".
Console.WriteLine(s1.LastIndexOf("\u00ADn"));
Console.WriteLine(s2.LastIndexOf("\u00ADn"));

// Find the index of the last soft hyphen followed by "m".
Console.WriteLine(s1.LastIndexOf("\u00ADm"));
Console.WriteLine(s2.LastIndexOf("\u00ADm"));

// The example displays the following output:
//
// 1
// 1
// 4
// 3

let s1 = "ani\u00ADmal"
let s2 = "animal"

// Find the index of the last soft hyphen followed by "n".
printfn $"""{s1.LastIndexOf "\u00ADn"}"""
printfn $"""{s2.LastIndexOf "\u00ADn"}"""

// Find the index of the last soft hyphen followed by "m".
printfn $"""{s1.LastIndexOf "\u00ADm"}"""
printfn $"""{s2.LastIndexOf "\u00ADm"}"""

// The example displays the following output:
//
// 1
// 1
// 4
// 3

Dim softHyphen As String = ChrW(&HAD)
Dim s1 As String = "ani" + softHyphen + "mal"
Dim s2 As String = "animal"

' Find the index of the last soft hyphen followed by "n".
Console.WriteLine(s1.LastIndexOf(softHyphen + "n"))
Console.WriteLine(s2.LastIndexOf(softHyphen + "n"))

' Find the index of the last soft hyphen followed by "m".
Console.WriteLine(s1.LastIndexOf(softHyphen + "m"))
Console.WriteLine(s2.LastIndexOf(softHyphen + "m"))

' The example displays the following output:
'
' 1
' 1
' 4
' 3

Poznámky pro volající

Jak je vysvětleno v osvědčených postupů pro používání řetězců, doporučujeme vyhnout se volání metod porovnání řetězců, které nahrazují výchozí hodnoty a místo toho volají metody, které vyžadují explicitní zadání parametrů. Pokud chcete najít poslední index podřetězce v instanci řetězce pomocí srovnávacích pravidel aktuální jazykové verze, signalizovat záměr explicitně voláním LastIndexOf(String, StringComparison) přetížení metody s hodnotou CurrentCulture pro jeho comparisonType parametr. Pokud nepotřebujete porovnání s lingvistiky, zvažte použití Ordinal.

Viz také

• Int32
• IndexOf(Char)
• IndexOfAny(Char[])
• LastIndexOfAny(Char[])

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

public:
 int LastIndexOf(char value);

public int LastIndexOf (char value);

member this.LastIndexOf : char -> int

Public Function LastIndexOf (value As Char) As Integer

Parametry

Návraty

Pozice indexu založeného na nule value, pokud je tento znak nalezen, nebo -1, pokud není.

Příklady

Následující příklad definuje ExtractFilename metodu, která používá metodu LastIndexOf(Char) k vyhledání posledního znaku oddělovače adresáře v řetězci a k extrahování názvu souboru řetězce. Pokud soubor existuje, vrátí metoda název souboru bez jeho cesty.

using System;
using System.IO;

public class TestLastIndexOf
{
   public static void Main()
   {
      string filename;
      
      filename = ExtractFilename(@"C:\temp\");
      Console.WriteLine("{0}", String.IsNullOrEmpty(filename) ? "<none>" : filename);
      
      filename = ExtractFilename(@"C:\temp\delegate.txt"); 
      Console.WriteLine("{0}", String.IsNullOrEmpty(filename) ? "<none>" : filename);

      filename = ExtractFilename("delegate.txt");      
      Console.WriteLine("{0}", String.IsNullOrEmpty(filename) ? "<none>" : filename);
      
      filename = ExtractFilename(@"C:\temp\notafile.txt");
      Console.WriteLine("{0}", String.IsNullOrEmpty(filename) ? "<none>" : filename);
   }

   public static string ExtractFilename(string filepath)
   {
      // If path ends with a "\", it's a path only so return String.Empty.
      if (filepath.Trim().EndsWith(@"\"))
         return String.Empty;
      
      // Determine where last backslash is.
      int position = filepath.LastIndexOf('\\');
      // If there is no backslash, assume that this is a filename.
      if (position == -1)
      {
         // Determine whether file exists in the current directory.
         if (File.Exists(Environment.CurrentDirectory + Path.DirectorySeparatorChar + filepath)) 
            return filepath;
         else
            return String.Empty;
      }
      else
      {
         // Determine whether file exists using filepath.
         if (File.Exists(filepath))
            // Return filename without file path.
            return filepath.Substring(position + 1);
         else
            return String.Empty;
      }
   }
}

open System
open System.IO

let extractFilename (filepath: string) =
    // If path ends with a "\", it's a path only so return String.Empty.
    if filepath.Trim().EndsWith @"\" then
        String.Empty
    else
        // Determine where last backslash is.
        let position = filepath.LastIndexOf '\\'
        // If there is no backslash, assume that this is a filename.
        if position = -1 then
            // Determine whether file exists in the current directory.
            if File.Exists(Environment.CurrentDirectory + string Path.DirectorySeparatorChar + filepath) then
                filepath
            else
                String.Empty
        else
            // Determine whether file exists using filepath.
            if File.Exists filepath then
            // Return filename without file path.
                filepath.Substring(position + 1)
            else
                String.Empty

do
    let filename = extractFilename @"C:\temp\"
    printfn $"""{if String.IsNullOrEmpty filename then "<none>" else filename}"""

    let filename = extractFilename @"C:\temp\delegate.txt"
    printfn $"""{if String.IsNullOrEmpty filename then "<none>" else filename}"""

    let filename = extractFilename "delegate.txt"
    printfn $"""{if String.IsNullOrEmpty filename then "<none>" else filename}"""

    let filename = extractFilename @"C:\temp\notafile.txt"
    printfn $"""{if String.IsNullOrEmpty filename then "<none>" else filename}"""

Imports System.IO

Public Module Test
   Public Sub Main()
      Dim filename As String 
      
      filename = ExtractFilename("C:\temp\")
      Console.WriteLine("{0}", IIf(String.IsNullOrEmpty(fileName), "<none>", filename))
      
      filename = ExtractFilename("C:\temp\delegate.txt") 
      Console.WriteLine("{0}", IIf(String.IsNullOrEmpty(fileName), "<none>", filename))

      filename = ExtractFilename("delegate.txt")      
      Console.WriteLine("{0}", IIf(String.IsNullOrEmpty(fileName), "<none>", filename))
      
      filename = ExtractFilename("C:\temp\notafile.txt")
      Console.WriteLine("{0}", IIf(String.IsNullOrEmpty(fileName), "<none>", filename))
   End Sub
   
   Public Function ExtractFilename(filepath As String) As String
      ' If path ends with a "\", it's a path only so return String.Empty.
      If filepath.Trim().EndsWith("\") Then Return String.Empty
      
      ' Determine where last backslash is.
      Dim position As Integer = filepath.LastIndexOf("\"c)
      ' If there is no backslash, assume that this is a filename.
      If position = -1 Then
         ' Determine whether file exists in the current directory.
         If File.Exists(Environment.CurrentDirectory + Path.DirectorySeparatorChar + filepath) Then
            Return filepath
         Else
            Return String.Empty
         End If
      Else
         ' Determine whether file exists using filepath.
         If File.Exists(filepath) Then
            ' Return filename without file path.
            Return filepath.Substring(position + 1)
         Else
            Return String.Empty
         End If                     
      End If
   End Function
End Module 
' The example displays the following output:
'        delegate.txt

Poznámky

Číslování indexů začíná od nuly. To znamená, že první znak v řetězci je na nule indexu a poslední je v Length - 1.

Tato metoda začne prohledávat poslední pozici znaku této instance a pokračuje směrem k začátku, dokud se nenajde value nebo se prozkoumá první pozice znaku. Hledání se rozlišují malá a velká písmena.

Tato metoda provádí řadové vyhledávání (bez rozlišení jazykové verze), kde se znak považuje za ekvivalentní jinému znaku pouze v případě, že skalární hodnoty Unicode jsou stejné. Chcete-li provést vyhledávání citlivé na jazykovou verzi, použijte metodu CompareInfo.LastIndexOf, kde skalární hodnota Unicode představující předkomposovaný znak, například ligaturu "Æ" (U+00C6), může být v závislosti na jazykové verzi považována za ekvivalentní jakémukoli výskytu součástí znaku ve správném pořadí, například "AE" (U+0041, U+0045).

Viz také

• Char
• IndexOf(Char)
• IndexOfAny(Char[])
• LastIndexOfAny(Char[])

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

Zdroj:

String.Searching.cs

public:
 int LastIndexOf(System::String ^ value, int startIndex);

public int LastIndexOf (string value, int startIndex);

member this.LastIndexOf : string * int -> int

Public Function LastIndexOf (value As String, startIndex As Integer) As Integer

Parametry

Návraty

Pozice počátečního indexu založeného na nule value, pokud se tento řetězec najde, nebo -1, pokud se nenajde nebo pokud se aktuální instance rovná Empty.

Výjimky

Příklady

Následující příklad najde index všech výskytů řetězce v cílovém řetězci, který pracuje od konce cílového řetězce až po začátek cílového řetězce.

// Sample for String::LastIndexOf(String, Int32)
using namespace System;
int main()
{
   String^ br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-";
   String^ br2 = "0123456789012345678901234567890123456789012345678901234567890123456";
   String^ str = "Now is the time for all good men to come to the aid of their party.";
   int start;
   int at;
   start = str->Length - 1;
   Console::WriteLine( "All occurrences of 'he' from position {0} to 0.", start );
   Console::WriteLine( "{0}\n{1}\n{2}\n", br1, br2, str );
   Console::Write( "The string 'he' occurs at position(s): " );
   at = 0;
   while ( (start > -1) && (at > -1) )
   {
      at = str->LastIndexOf( "he", start );
      if ( at > -1 )
      {
         Console::Write( " {0} ", at );
         start = at - 1;
      }
   }

   Console::WriteLine();
}

/*
This example produces the following results:
All occurrences of 'he' from position 66 to 0.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The string 'he' occurs at position(s):  56  45  8
*/

// Sample for String.LastIndexOf(String, Int32)
using System;

class Sample {
    public static void Main() {

    string br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-";
    string br2 = "0123456789012345678901234567890123456789012345678901234567890123456";
    string str = "Now is the time for all good men to come to the aid of their party.";
    int start;
    int at;

    start = str.Length-1;
    Console.WriteLine("All occurrences of 'he' from position {0} to 0.", start);
    Console.WriteLine("{1}{0}{2}{0}{3}{0}", Environment.NewLine, br1, br2, str);
    Console.Write("The string 'he' occurs at position(s): ");

    at = 0;
    while((start > -1) && (at > -1))
        {
        at = str.LastIndexOf("he", start);
        if (at > -1)
            {
            Console.Write("{0} ", at);
            start = at - 1;
            }
        }
    Console.Write("{0}{0}{0}", Environment.NewLine);
    }
}
/*
This example produces the following results:
All occurrences of 'he' from position 66 to 0.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The string 'he' occurs at position(s): 56 45 8


*/

// Sample for String.LastIndexOf(String, Int32)
open System

let br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-"
let br2 = "0123456789012345678901234567890123456789012345678901234567890123456"
let str = "Now is the time for all good men to come to the aid of their party."

let mutable start = str.Length - 1
printfn $"All occurrences of 'he' from position {start} to 0." 
printfn $"{br1}{Environment.NewLine}{br2}{Environment.NewLine}{str}{Environment.NewLine}"
printf "The string 'he' occurs at position(s): "

let mutable at = 0
while (start > -1) && (at > -1) do
    at <- str.LastIndexOf("he", start)
    if at > -1 then
        printf $"{at} "
        start <- at - 1
printf $"{Environment.NewLine}{Environment.NewLine}{Environment.NewLine}"
(*
This example produces the following results:
All occurrences of 'he' from position 66 to 0.
0----+----1----+----2----+----3----+----4----+----5----+----6----+-
0123456789012345678901234567890123456789012345678901234567890123456
Now is the time for all good men to come to the aid of their party.

The string 'he' occurs at position(s): 56 45 8


*)

' Sample for String.LastIndexOf(String, Int32)
 _

Class Sample
   
   Public Shared Sub Main()
      
      Dim br1 As String = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-"
      Dim br2 As String = "0123456789012345678901234567890123456789012345678901234567890123456"
      Dim str As String = "Now is the time for all good men to come to the aid of their party."
      Dim start As Integer
      Dim at As Integer

      '#3
      start = str.Length - 1
      Console.WriteLine("All occurrences of 'he' from position {0} to 0.", start)
      Console.WriteLine("{1}{0}{2}{0}{3}{0}", Environment.NewLine, br1, br2, str)
      Console.Write("The string 'he' occurs at position(s): ")
      
      at = 0
      While start > - 1 And at > - 1
         at = str.LastIndexOf("he", start)
         If at > - 1 Then
            Console.Write("{0} ", at)
            start = at - 1
         End If
      End While
      Console.Write("{0}{0}{0}", Environment.NewLine)
   End Sub
End Class
'
'This example produces the following results:
'All occurrences of 'he' from position 66 to 0.
'0----+----1----+----2----+----3----+----4----+----5----+----6----+-
'0123456789012345678901234567890123456789012345678901234567890123456
'Now is the time for all good men to come to the aid of their party.
'
'The string 'he' occurs at position(s): 56 45 8
'
'

Poznámky

Číslování indexů začíná od nuly. To znamená, že první znak v řetězci je na nule indexu a poslední je v Length - 1.

Hledání začíná na startIndex pozici znaku této instance a pokračuje směrem k začátku, dokud se nenajde value nebo se prozkoumá první pozice znaku. Pokud je například startIndexLength - 1, metoda vyhledá každý znak od posledního znaku v řetězci na začátek.

Tato metoda provádí hledání slov (rozlišujících velká a malá písmena a jazykové verze) pomocí aktuální jazykové verze.

Znakové sady obsahují ignorovatelné znaky, což jsou znaky, které se při provádění jazykového nebo jazykového porovnání nerozlišují. Pokud v hledání citlivém na jazykovou verzi value obsahuje ignorovatelný znak, výsledek odpovídá hledání s odebraným znakem. V následujícím příkladu se metoda LastIndexOf(String, Int32) používá k vyhledání podřetězce, který obsahuje měkký spojovník (U+00AD) a který předchází nebo obsahuje konečný řetězec "m". Pokud je příklad spuštěn v rozhraní .NET Framework 4 nebo novější, protože měkký spojovník ve vyhledávacím řetězci je ignorován, volání metody k vyhledání podřetězce, která se skládá z měkkého spojovníku a "m" vrátí pozici "m" v řetězci, zatímco volání k nalezení podřetězce, který se skládá z měkké spojovníku a "n" vrátí pozici "n".

int position = 0;
string s1 = "ani\u00ADmal";
string s2 = "animal";

// Find the index of the soft hyphen followed by "n".
position = s1.LastIndexOf("m");
Console.WriteLine($"'m' at position {position}");

if (position >= 0)
    Console.WriteLine(s1.LastIndexOf("\u00ADn", position));

position = s2.LastIndexOf("m");
Console.WriteLine($"'m' at position {position}");

if (position >= 0)
    Console.WriteLine(s2.LastIndexOf("\u00ADn", position));

// Find the index of the soft hyphen followed by "m".
position = s1.LastIndexOf("m");
Console.WriteLine($"'m' at position {position}");

if (position >= 0)
    Console.WriteLine(s1.LastIndexOf("\u00ADm", position));

position = s2.LastIndexOf("m");
Console.WriteLine($"'m' at position {position}");

if (position >= 0)
    Console.WriteLine(s2.LastIndexOf("\u00ADm", position));

// The example displays the following output:
//
// 'm' at position 4
// 1
// 'm' at position 3
// 1
// 'm' at position 4
// 4
// 'm' at position 3
// 3

let s1 = "ani\u00ADmal"
let s2 = "animal"

// Find the index of the soft hyphen followed by "n".
let position = s1.LastIndexOf "m"
printfn $"'m' at position {position}"

if position >= 0 then
    printfn $"""{s1.LastIndexOf("\u00ADn", position)}"""

let position = s2.LastIndexOf "m"
printfn $"'m' at position {position}"

if position >= 0 then
    printfn $"""{s2.LastIndexOf("\u00ADn", position)}"""

// Find the index of the soft hyphen followed by "m".
let position = s1.LastIndexOf "m"
printfn $"'m' at position {position}"

if position >= 0 then
    printfn $"""{s1.LastIndexOf("\u00ADm", position)}"""

let position = s2.LastIndexOf "m"
printfn $"'m' at position {position}"

if position >= 0 then
    printfn $"""{s2.LastIndexOf("\u00ADm", position)}"""
// The example displays the following output:
//
// 'm' at position 4
// 1
// 'm' at position 3
// 1
// 'm' at position 4
// 4
// 'm' at position 3
// 3

Dim position As Integer
Dim softHyphen As String = ChrW(&HAD)
Dim s1 As String = "ani" + softHyphen + "mal"
Dim s2 As String = "animal"

' Find the index of the soft hyphen followed by "n".
position = s1.LastIndexOf("m")
Console.WriteLine($"'m' at position {position}")

If position >= 0 Then
    Console.WriteLine(s1.LastIndexOf(softHyphen + "n", position))
End If

position = s2.LastIndexOf("m")
Console.WriteLine($"'m' at position {position}")

If position >= 0 Then
    Console.WriteLine(s2.LastIndexOf(softHyphen + "n", position))
End If

' Find the index of the soft hyphen followed by "m".
position = s1.LastIndexOf("m")
Console.WriteLine($"'m' at position {position}")

If position >= 0 Then
    Console.WriteLine(s1.LastIndexOf(softHyphen + "m", position))
End If

position = s2.LastIndexOf("m")
Console.WriteLine($"'m' at position {position}")

If position >= 0 Then
    Console.WriteLine(s2.LastIndexOf(softHyphen + "m", position))
End If

' The example displays the following output:
'
' 'm' at position 4
' 1
' 'm' at position 3
' 1
' 'm' at position 4
' 4
' 'm' at position 3
' 3

Poznámky pro volající

Jak je vysvětleno v osvědčených postupů pro používání řetězců, doporučujeme vyhnout se volání metod porovnání řetězců, které nahrazují výchozí hodnoty a místo toho volají metody, které vyžadují explicitní zadání parametrů. Chcete-li najít index podřetětěce, který předchází určité pozici znaku pomocí srovnávacích pravidel aktuální jazykové verze, signalizujete záměr explicitně voláním přetížení metody LastIndexOf(String, Int32, StringComparison) s hodnotou CurrentCulture pro jeho comparisonType parametr. Pokud nepotřebujete porovnání s lingvistiky, zvažte použití Ordinal.

Viz také

• Int32
• IndexOf(Char)
• IndexOfAny(Char[])
• LastIndexOfAny(Char[])