Regex.Replace Method (String, String, MatchEvaluator)

Parameters

• input
  Type: System.String
  The string to search for a match.

• pattern
  Type: System.String
  The regular expression pattern to match.

• evaluator
  Type: System.Text.RegularExpressions.MatchEvaluator
  A custom method that examines each match and returns either the original matched string or a replacement string.

Return Value

Type: System.String
A new string that is identical to the input string, except that a replacement string takes the place of each matched string.

Public Function MatchEvaluatorMethod(ByVal match As Match) As String

public string MatchEvaluatorMethod(Match match)

Imports System.Collections.Generic
Imports System.Text.RegularExpressions

Module Example
   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim words As String = "letter alphabetical missing lack release " + _
                            "penchant slack acryllic laundry cease"
      Dim pattern As String = "\w+"
      Dim evaluator As MatchEvaluator = AddressOf WordScrambler
      outputBlock.Text &= "Original words:" & vbCrLf
      outputBlock.Text &= words & vbCrLf
      outputBlock.Text &= "Scrambled words:" & vbCrLf
      outputBlock.Text &= Regex.Replace(words, pattern, evaluator) & vbCrLf
   End Sub

   Public Function WordScrambler(ByVal match As Match) As String
      Dim arraySize As Integer = match.Value.Length - 1
      ' Define two arrays equal to the number of letters in the match.
      Dim keys(arraySize) As Double
      Dim letters(arraySize) As Char

      ' Instantiate random number generator'
      Dim rnd As New Random()

      For ctr As Integer = 0 To match.Value.Length - 1
         ' Populate the array of keys with random numbers.
         keys(ctr) = rnd.NextDouble()
         ' Assign letter to array of letters.
         letters(ctr) = match.Value.Chars(ctr)
      Next
      Array.Sort(keys, letters, 0, arraySize, Comparer(Of Double).Default)
      Return New String(letters)
   End Function
End Module
' The example displays output similar to the following:
'    Original words:
'    letter alphabetical missing lack release penchant slack acryllic laundry cease
'    
'    Scrambled words:
'    elrtte iaeabatlpchl igmnssi lcka aerslee hnpatnce ksacl lialcryc dylruna ecase

using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      string words = "letter alphabetical missing lack release " +
                     "penchant slack acryllic laundry cease";
      string pattern = @"\w+";
      MatchEvaluator evaluator = new MatchEvaluator(WordScrambler);
      outputBlock.Text += "Original words:" + "\n";
      outputBlock.Text += words + "\n";
      outputBlock.Text += "\n";
      outputBlock.Text += "Scrambled words:" + "\n";
      outputBlock.Text += Regex.Replace(words, pattern, evaluator) + "\n";
   }

   public static string WordScrambler(Match match)
   {
      int arraySize = match.Value.Length;
      // Define two arrays equal to the number of letters in the match.
      double[] keys = new double[arraySize];
      char[] letters = new char[arraySize];

      // Instantiate random number generator'
      Random rnd = new Random();

      for (int ctr = 0; ctr < match.Value.Length; ctr++)
      {
         // Populate the array of keys with random numbers.
         keys[ctr] = rnd.NextDouble();
         // Assign letter to array of letters.
         letters[ctr] = match.Value[ctr];
      }
      Array.Sort(keys, letters, 0, arraySize, Comparer<Double>.Default);
      return new String(letters);
   }
}
// The example displays output similar to the following:
//    Original words:
//    letter alphabetical missing lack release penchant slack acryllic laundry cease
//    
//    Scrambled words:
//    elrtte iaeabatlpchl igmnssi lcka aerslee hnpatnce ksacl lialcryc dylruna ecase