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

.NET Framework Class Library

Regex..::.Replace Method (String, String, MatchEvaluator, RegexOptions)

Updated: July 2009

Within a specified input string, replaces all strings that match a specified regular expression with a string returned by a MatchEvaluator delegate. Specified options modify the matching operation.

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

Syntax

Visual Basic (Declaration)

Public Shared Function Replace ( _
    input As String, _
    pattern As String, _
    evaluator As MatchEvaluator, _
    options As RegexOptions _
) As String

Visual Basic (Usage)

Dim input As String
Dim pattern As String
Dim evaluator As MatchEvaluator
Dim options As RegexOptions
Dim returnValue As String

returnValue = Regex.Replace(input, _
    pattern, evaluator, options)

public static string Replace(
    string input,
    string pattern,
    MatchEvaluator evaluator,
    RegexOptions options
)

Visual C++

public:
static String^ Replace(
    String^ input, 
    String^ pattern, 
    MatchEvaluator^ evaluator, 
    RegexOptions options
)

JScript

public static function Replace(
    input : String, 
    pattern : String, 
    evaluator : MatchEvaluator, 
    options : RegexOptions
) : String

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.

options: Type: System.Text.RegularExpressions..::.RegexOptions
A bitwise OR combination of the enumeration values.

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.

Exceptions

Exception	Condition
ArgumentException	A regular expression parsing error has occurred.
ArgumentNullException	input is nullNothingnullptra null reference (Nothing in Visual Basic). -or- pattern is nullNothingnullptra null reference (Nothing in Visual Basic). -or- evaluator is nullNothingnullptra null reference (Nothing in Visual Basic).
ArgumentOutOfRangeException	options is not a valid bitwise combination of RegexOptions values.

Exception

Condition

ArgumentException

A regular expression parsing error has occurred.

ArgumentNullException

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

-or-

pattern is nullNothingnullptra null reference (Nothing in Visual Basic).

-or-

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

ArgumentOutOfRangeException

options is not a valid bitwise combination of RegexOptions values.

Remarks

The Regex..::.Replace(String, String, MatchEvaluator, RegexOptions) method is useful for replacing a regular expression match in if any of the following conditions is true:

The replacement string cannot readily be specified by a regular expression replacement pattern.
The replacement string results from some processing done on the matched string.
The replacement string results from conditional processing.

The method is equivalent to calling the Regex..::.Matches(String, String, RegexOptions) method and passing each Match object in the returned MatchCollection collection to the evaluator delegate.

The pattern parameter consists of various regular expression language elements that symbolically describe the string to match. For more information about regular expressions, see .NET Framework Regular Expressions and Regular Expression Language Elements.

The evaluator parameter is the delegate for a custom method that you define and that examines each match. The custom method must have the following signature to match the MatchEvaluator delegate.

Visual Basic

Public Function MatchEvaluatorMethod(match As Match) As String
   Return String.Empty
End Function

Your custom method returns a string that replaces the matched input.

If the options parameter specifies the RightToLeft enumeration value, the search for matches begins from the end of the input string and proceeds from right to left; otherwise, the search begins from the start of the input string and proceeds from left to right.

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

Version Information