Replace with regex keeping part of the pattern

Question

In the example below, how to preserve part of a pattern? The pattern search must include closing tag </h3> as spans elsewhere must not be targeted.

Example: remove only </span> from </span> some text </h3>:

regEx.Pattern = "</span>[^>]*</h3>"
hr2 = regEx.Replace(hr2,"[^>]*</h3>")  '<- does not work

Try regEx.Pattern = "</span>([^>]*)</h3>" // hr2 = regEx.Replace(hr2,"$1</h3>") — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Jul 22, 2015 at 14:55
This did the same as what did not work above - passed it through, in this case as '$1'. — Paul
– Paul, Commented Jul 22, 2015 at 15:12
Sorry, your solution correct. Did not notice the brackets in the pattern above that make $1 work. Thanks for fast help! — Paul
– Paul, Commented Jul 22, 2015 at 15:17

Wiktor Stribiżew · Accepted Answer · 2015-07-22 15:34:32Z

3

You need to set a capturing group and use a back reference in the replacement pattern.

regEx.Pattern = "</span>([^>]*)</h3>"
hr2 = regEx.Replace(hr2,"$1</h3>")

Or

regEx.Pattern = "</span>([^>]*</h3>)"
hr2 = regEx.Replace(hr2,"$1")

answered Jul 22, 2015 at 15:34

Wiktor Stribiżew

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3 Comments

It may be worth considering using the non-greedy expression .*? instead of [^>]* in case there are other tags between </span> and </h3>.

Yes, but we do not know the input text. Surely .*? will also capture the tags before </h3> then.

</span>(.*?)</h3> would capture tags between </span> and </h3>, yes.