In a specified input string, replaces all strings that match a specified regular expression with a string returned by a System.Text.RegularExpressions.MatchEvaluator delegate.
Syntax
Parameters
- input
- evaluator
Returns
A new string that is identical to the input string, except that a replacement string takes the place of each matched string. If the regular expression pattern is not matched in the current instance, the method returns the current instance unchanged.
Remarks
The Regex.Replace(string, MatchEvaluator) 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) method and passing each System.Text.RegularExpressions.Match object in the returned System.Text.RegularExpressions.MatchCollection collection to the evaluator delegate.
The regular expression is the pattern defined by the constructor for the current System.Text.RegularExpressions.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 System.Text.RegularExpressions.MatchEvaluator delegate.
code reference: System.Text.RegularExpressions.Regex.Replace#1
Your custom method returns a string that replaces the matched input.
The System.Text.RegularExpressions.RegexMatchTimeoutException exception is thrown if the execution time of the replacement operation exceeds the time-out interval specified by the Regex.#ctor(string, RegexOptions, TimeSpan) constructor. If you do not set a time-out interval when you call the constructor, the exception is thrown if the operation exceeds any time-out value established for the application domain in which the System.Text.RegularExpressions.Regex object is created. If no time-out is defined in the System.Text.RegularExpressions.Regex constructor call or in the application domain's properties, or if the time-out value is Regex.InfiniteMatchTimeout, no exception is thrown
Because the method returns input unchanged if there is no match, you can use the object.ReferenceEquals(object, object) method to determine whether the method has made any replacements to the input string.
Requirements
Assembly: System (in System.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0, 4.0.0.0