Regex .NET question

Question

Is it possible using Regex.Replace to match a string, but only replace a portion of that matched string? Some way to mark part of the string that should be replaced with the replacement text parameter?

Community · Accepted Answer · 2020-06-20 09:12:55Z

5

You can use groups to insert parts of the original string, or you can use lookbehind and lookahead.

Examples

Using Groups:

someString = Regex.Replace(someString, @"(before)content(after)", "$1new content$2");

Using lookaround:

someString = Regex.Replace(someString, @"(?<=before)content(?=after)", @"new content");

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Jul 14, 2010 at 20:15

SLaks

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4 Comments

Winforms Over a year ago

Looking forward to the examples :)

Winforms Over a year ago

Works but instead of \1 you need $1

Winforms Over a year ago

@SLaks: Why do you have the ?<= and the ?=, without them everything works perfect. With them it doesn't work.

SLaks Over a year ago

@Winforms: Those are lookaround assertions. It works for me: Regex.Replace("abc", @"(?<=a)b(?=c)", "q") prints aqc.

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