Represents the method that is called each time a regular expression match is found during a Replace method operation.
Assembly: System (in System.dll)
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 Example Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock) 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. outputBlock.Text &= sInput & vbCrLf ' Replace matched characters using the delegate method. sInput = r.Replace(sInput, myEvaluator) ' Write out the modified string. outputBlock.Text &= sInput & vbCrLf 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 += 1 Return i.ToString() & i.ToString() End Function End Module ' The example displays the following output: ' aabbccddeeffcccgghhcccciijjcccckkcc ' aabb11ddeeff22cgghh3344iijj5566kk77
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