Represents the method that is called each time a regular expression match is found during a Replace method operation.
Assembly: System (in System.dll)
'Declaration <SerializableAttribute> _ Public Delegate Function MatchEvaluator ( _ match As Match _ ) As String
Return ValueType: System.String
A string returned by the method that is represented by the delegate.
You can use a delegate method to perform a custom verification or manipulation operation for each match found by a replacement method such as Regex.Replace(String, MatchEvaluator). For each matched string, the Replace method calls the delegate method with a Match object that represents the match. The delegate method performs whatever processing you prefer and returns a string that the Replace method substitutes for the matched string.
The following code example uses the delegate to replace every matched group of characters with the number of the match occurrence.
Imports System.Text.RegularExpressions Module Module1 Public Sub Main() Dim sInput, sRegex As String ' The string to search. sInput = "aabbccddeeffcccgghhcccciijjcccckkcc" ' A very simple regular expression. sRegex = "cc" Dim r As Regex = New Regex(sRegex) ' Assign the replace method to the MatchEvaluator delegate. Dim myEvaluator As MatchEvaluator = New MatchEvaluator(AddressOf ReplaceCC) ' Write out the original string. Console.WriteLine(sInput) ' Replace matched characters using the delegate method. sInput = r.Replace(sInput, myEvaluator) ' Write out the modified string. Console.WriteLine(sInput) End Sub Public Function ReplaceCC(ByVal m As Match) As String ' Replace each Regex match with the number of the match occurrence. static i as integer i = i + 1 Return i.ToString() & i.ToString() End Function End Module ' The example displays the following output: ' aabbccddeeffcccgghhcccciijjcccckkcc ' aabb11ddeeff22cgghh3344iijj5566kk77
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.