Regex.Replace Method (String, MatchEvaluator, Int32, Int32)

Within a specified input substring, replaces a specified maximum number of strings that match a regular expression pattern with a string returned by a MatchEvaluator delegate.

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

String^ Replace (
	String^ input, 
	MatchEvaluator^ evaluator, 
	int count, 
	int startat
public String Replace (
	String input, 
	MatchEvaluator evaluator, 
	int count, 
	int startat
public function Replace (
	input : String, 
	evaluator : MatchEvaluator, 
	count : int, 
	startat : int
) : String
Not applicable.



The string to search for a match.


A custom method that examines each match and returns either the original matched string or a replacement string.


The maximum number of times the replacement will occur.


The character position in the input string where the search begins.

Return Value

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

Exception typeCondition


input is a null reference (Nothing in Visual Basic).


evaluator is a null reference (Nothing in Visual Basic).

The regular expression is the pattern defined by the constructor for the current Regex object. The evaluator parameter is the delegate for a custom method that you define and that examines each match. Your custom method returns a string that replaces the matched input.

Windows 98, Windows Server 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 Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0