using .NET Regex.Replace() to replace expression more than once

Question

I couldn't seem to find a match for this question so my apologies in advance if it's a duplicate.

Given the template: <<FirstName>> << FirstName >>

I want to replace both strings between the '<<>>''s using a single regex that should match both.

The following code doesn't seem to work the way I'm expecting:

[Test]
public void ShouldReplaceMultiple()
{
  var pattern = "<<.*FirstName.*>>";
  var template = "<<FirstName>> <<FirstName>>";
  var replaceWith = "FOO";

  var regex = new Regex(pattern); 

  Assert.AreEqual("FOO FOO", regex.Replace(template, replaceWith));
}

The output of the test is as follows:

Expected string length 7 but was 3. Strings differ at index 3.
  Expected: "FOO FOO"
  But was:  "FOO"
  --------------^

I don't understand why both strings won't be replaced?

rock321987 · Answer 1 · 2016-04-15T06:08:43.187

3

Make it non-greedy using .*?

var pattern = "<<.*?FirstName.*?>>";
var template = "<<FirstName>> <<FirstName>>";
var replaceWith = "FOO";

var regex = new Regex(pattern); 

Console.WriteLine(regex.Replace(template, replaceWith));

Ideone Demo

If you want to deal only with spaces in between the <<>>, then this will suffice

<<\s*?FirstName\s*?>>

edited Apr 15 '16 at 06:08

answered Apr 15 '16 at 05:34

rock321987

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<> is matched by your pattern. – M.S. Apr 15 '16 at 05:38
@M.S. as per OP :- `I want to replace both strings between the '<<>>''s using a single regex `..also OP is using `.*` in pattern – rock321987 Apr 15 '16 at 05:40

score 1 · Accepted Answer · answered Apr 15 '16 at 05:37

1

string pattern = @"<<(?<=<<)\s*FirstName\s*(?=>>)>>";
var template = "<<FirstName>> <<FirstName>>";
var replaceWith = "FOO";

var regex = new Regex(pattern); 

Assert.AreEqual("FOO FOO", regex.Replace(template, replaceWith));

answered Apr 15 '16 at 05:37

M.S.

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using .NET Regex.Replace() to replace expression more than once

2 Answers2