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How Do I...Use Regular Expressions to make replacements?



The Regular Expressions library can often ease the time it takes to generate string replacement functions. By specifying a pattern of strings to be replaced, you do not have to search for every possible variation of a string. Once a Regex object that matches every possible string to be replaced is created, the Replace method can be used to generate a result. The Replace method can be most easily used by passing in the source string and the replacement string. The Replace method will return the results as a String.

Regex digitregex = new Regex("(?<digit>[0-9])"); String before = "Here is so4848me te88xt with emb4493edded numbers."; ... String after = digitregex.Replace(before, ""); Dim digitregex As Regex = new Regex("(?<digit>[0-9])") Dim Before As String = "Here is so4848me te88xt with emb4493edded numbers." ... Dim After As String = DigitRegex.Replace(Before, "") Regex * digitregex = new Regex(S"(?[0-9])"); String * before = S"Here is so4848me te88xt with emb4493edded numbers."; ... String * after = digitregex -> Replace(before, "");

You can also reuse the matched string in the replacement. In the previous snippet we have a named capture of ?<digit>. This named capture can be reused in the replacement string as ${digit}. Note that ordinal captures can be used as well, $123, which would evaluate to 123 captures in our pattern.

This example illustrates how to use the Replace method of Regex to remove all digits from the input string.

Example