Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8

Function

  • Match
  • Substitution
  • List
  • Unit Tests
/
<!--((.[\r\n])|(.))*?-->
/
g
<!--
matches the characters <!-- literally (case sensitive)
1st Capturing Group
((.[\r\n])|(.))*?
*? matches the previous token between zero and unlimited times, as few times as possible, expanding as needed (lazy)
A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you're not interested in the data
1st Alternative
(.[\r\n])
2nd Capturing Group
(.[\r\n])
. matches any character (except for line terminators)
Match a single character present in the list below
[\r\n]
\r matches a carriage return (ASCII 13)
\n matches a line-feed (newline) character (ASCII 10)
2nd Alternative
(.)
3rd Capturing Group
(.)
. matches any character (except for line terminators)
-->
matches the characters --> literally (case sensitive)
Global pattern flags
g modifier: global. All matches (don't return after first match)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
g

Test String