Regex.Replace Method (String, MatchEvaluator, Int32, Int32)
Updated: July 2009
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.
Assembly: System (in System.dll)
'Declaration Public Function Replace ( _ input As String, _ evaluator As MatchEvaluator, _ count As Integer, _ startat As Integer _ ) As String 'Usage Dim instance As Regex Dim input As String Dim evaluator As MatchEvaluator Dim count As Integer Dim startat As Integer Dim returnValue As String returnValue = instance.Replace(input, _ evaluator, count, startat)
Parameters
- input
- Type: System.String
The string to search for a 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.
- count
- Type: System.Int32
The maximum number of times the replacement will occur.
- startat
- Type: System.Int32
The character position in the input string where the search begins.
Return Value
Type: System.StringA new string that is identical to the input string, except that a replacement string takes the place of each matched string.
| Exception | Condition |
|---|---|
| ArgumentNullException | input is Nothing. -or- evaluator is Nothing. |
| ArgumentOutOfRangeException | startat is less than zero or greater than the length of input. |
The Regex.Replace(String, MatchEvaluator, Int32, Int32) method is useful for replacing a regular expression match 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, Int32) method and passing the first count Match objects in the returned MatchCollection collection to the evaluator delegate.
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. The custom method must have the following signature to match the MatchEvaluator delegate.
Your custom method returns a string that replaces the matched input.
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.