====== Regex ======

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|desc=Document the syntax of **regex**.}}

===== Control which part of the matched string should be returned. =====

<codeprism>
EXP1(?=EXP2)

(?<=EXP2)EXP1

EXP1(?!EXP2)

</codeprism>

The string must match ''EXP1'' and ''EXP2'', but only the part of the string that matches ''EXP1'' is returned.