String.LastIndexOf Method (Char, Int32, Int32)

Parameters

• value
  Type: System.Char
  A Unicode character to seek.

• startIndex
  Type: System.Int32
  The starting position of a substring within this instance.

• count
  Type: System.Int32
  The number of character positions to examine.

Return Value

Type: System.Int32
The zero-based index position of value if that character is found, or -1 if it is not found or if the current instance equals String.Empty.

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

Class Example

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      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
      outputBlock.Text &= String.Format("All occurrences of 't' from position {0} to {1}.", start, [end]) & vbCrLf
      outputBlock.Text &= String.Format("{1}{0}{2}{0}{3}{0}", vbCrLf, br1, br2, str) & vbCrLf
      outputBlock.Text &= "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
            outputBlock.Text &= String.Format("{0} ", at)
            start = at - 1
         End If
      End While
      outputBlock.Text &= String.Format("{0}{0}{0}", vbCrLf)
   End Sub 'Main 
End Class 'Sample
'
'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 Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {

      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;
      outputBlock.Text += String.Format("All occurrences of 't' from position {0} to {1}.", start, end) + "\n";
      outputBlock.Text += String.Format("{1}{0}{2}{0}{3}{0}", "\n", br1, br2, str) + "\n";
      outputBlock.Text += "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)
         {
            outputBlock.Text += String.Format("{0} ", at);
            start = at - 1;
         }
      }
      outputBlock.Text += String.Format("{0}{0}{0}", "\n");
   }
}
/*
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


*/