Regex.Replace Method (String, MatchEvaluator) (System.Text.RegularExpressions)

.NET Framework Class Library

Regex.Replace Method (String, MatchEvaluator)

Replaces all occurrences of a character pattern defined by the regular expression specified in the Regex constructor. A MatchEvaluator delegate is called at each match to evaluate the replacement.

Namespace: System.Text.RegularExpressions
Assembly: System (in system.dll)

Syntax

Visual Basic (Declaration)

Public Function Replace ( _
    input As String, _
    evaluator As MatchEvaluator _
) As String

Visual Basic (Usage)

Dim instance As Regex
Dim input As String
Dim evaluator As MatchEvaluator
Dim returnValue As String

returnValue = instance.Replace(input, evaluator)

public string Replace (
    string input,
    MatchEvaluator evaluator
)

C++

public:
String^ Replace (
    String^ input, 
    MatchEvaluator^ evaluator
)

public String Replace (
    String input, 
    MatchEvaluator evaluator
)

JScript

public function Replace (
    input : String, 
    evaluator : MatchEvaluator
) : String

Parameters

input: The string to modify.

evaluator: The MatchEvaluator which evaluates replacement at each step.

Return Value

The modified character string.

Remarks

The MatchEvaluator type is a delegate that takes a single Match as input and returns a string. It is declared as follows:

public delegate String RegexMatchEvaluator(Match match);

The delegate is called once per match during a replace.

Example

The following code example displays an original string, matches each word in the original string, converts the first character of each match to uppercase, then displays the converted string.

Visual Basic

Imports System.Text.RegularExpressions

Class RegExSample
   Shared Function CapText(m As Match) As String
      ' Get the matched string.
      Dim x As String = m.ToString()
      ' If the first char is lower case...
      If Char.IsLower(x.Chars(0)) Then
         ' Capitalize it.
         Return Char.ToUpper(x.Chars(0)) & x.Substring(1, x.Length - 1)
      End If
      Return x
   End Function    
    
   Public Shared Sub Main()
      Dim text As String = "four score and seven years ago"
      System.Console.WriteLine("text=[" & text & "]")
      Dim result As String = Regex.Replace(text, "\w+", _
         AddressOf RegExSample.CapText)
      System.Console.WriteLine("result=[" & result & "]")
   End Sub
End Class

using System.Text.RegularExpressions;

class RegExSample 
{
   static string CapText(Match m) 
   {
      // Get the matched string.
      string x = m.ToString();
      // If the first char is lower case...
      if (char.IsLower(x[0])) 
      {
         // Capitalize it.
         return char.ToUpper(x[0]) + x.Substring(1, x.Length-1);
      }
      return x;
   }
    
   static void Main() 
   {
      string text = "four score and seven years ago";
      System.Console.WriteLine("text=[" + text + "]");
      string result = Regex.Replace(text, @"\w+",
         new MatchEvaluator(RegExSample.CapText));
      System.Console.WriteLine("result=[" + result + "]");
   }
}

C++

#using <System.dll>

using namespace System;
using namespace System::Text::RegularExpressions;

ref class RegExSample
{
public:
   static String^ CapText( Match^ m )
   {
      // Get the matched String.
      String^ x = m->ToString();
      
      // If the first char is lower case...
      if ( Char::IsLower( x[ 0 ] ) )
      {
         // Capitalize it.
         return Char::ToUpper( x[ 0 ] ) + x->Substring( 1, x->Length - 1 );
      }

      return x;
   }
};

int main()
{
   String^ text = "four score and seven years ago";
   Console::WriteLine( "text=[{0}]", text );
   String^ result = Regex::Replace( text, "\\w+", gcnew MatchEvaluator( &RegExSample::CapText ) );
   System::Console::WriteLine( "result=[{0}]", result );
}

import System.Text.RegularExpressions.*;

class RegExSample
{
    static String CapText(Match m)
    {
        // Get the matched string.
        String x = m.ToString();

        // If the first char is lower case...
        if (System.Char.IsLower(x.charAt(0))) {
            // Capitalize it.
            return System.Char.ToUpper(x.charAt(0)) 
                + x.Substring(1, x.get_Length() - 1);
        }
        return x;
    } //CapText

    public static void main(String[] args)
    {
        String text = "four score and seven years ago";
        System.Console.WriteLine("text=[" + text + "]");
        String result = Regex.Replace(text, "\\w+", 
            new MatchEvaluator(RegExSample.CapText));
        System.Console.WriteLine("result=[" + result + "]");
    } //main
} //RegExSample

JScript

import System.Text.RegularExpressions;

class RegExSample 
{ 
   static function CapText(m : Match) : String  
   {
      // get the matched string.
      var x : String = m.ToString();
      // If the first char is lower case...
      if (System.Char.IsLower(x[0])) 
      {
         // Capitalize it.
         return System.Char.ToUpper(x[0]) + x.Substring(1, x.Length-1);
      }
      return x;
   }
    
   static function Main() : void 
   {
      var text : String = "four score and seven years ago";
      System.Console.WriteLine("text=[" + text + "]");
      var result : String = Regex.Replace(text, "\\w+", RegExSample.CapText);
      System.Console.WriteLine("result=[" + result + "]");
   }
}
RegExSample.Main();

Platforms

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

Version Information

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

Reference

Regex Class
Regex Members
System.Text.RegularExpressions Namespace