Regular Expressions 101

Group 1(<TopicSet.*?>)

<TopicSetthe literal text <TopicSet (case sensitive)

.*?any character (except for line terminators), repeated any number of times

>the literal > (62₁₀ / 76₈ / 3E₁₆)

Group 2([\s\S]*?)

Character Class[\s\S]*?

*?matches any number of characters from the set below:

\sany whitespace character

\Sany non-whitespace character

Group 3(<\/TopicSet>)

<the literal < (60₁₀ / 74₈ / 3C₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

TopicSet>the literal text TopicSet> (case sensitive)

Global pattern flags

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

g modifier: global. Finds all matches instead of stopping after the first

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

(<TopicSet.*?>)([\s\S]*?)(<\/TopicSet>)

New

<TopicSet FormalName="PARENT1">
	<Topic>
	  <TopicType FormalName="Child1" />
	</Topic>
	<Topic>
	  <TopicType FormalName="Child2" />
	</Topic>
	<Topic>
	  <TopicType FormalName="Child3" />
	</Topic>
</TopicSet>
<TopicSet FormalName="PARENT2">
	<Topic>
	  <TopicType FormalName="Child1" />
	</Topic>
	<Topic>
	  <TopicType FormalName="Child2" />
	</Topic>
	<Topic>
	  <TopicType FormalName="Child3" />
	</Topic>
</TopicSet>

Substitution

$2