Regular Expressions 101

Save & Share

  • Save Regex
    ctrl+s
  • Update Regex
    ctrl+⇧+s

Flavor

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

Function

  • Match
  • Substitution
  • List
  • Unit Tests
~
<\?(?:php)? (?:(?!\?>)[\s\S])* (?:\?>)?
~
gmx
< matches the character < with index 6010 (3C16 or 748) literally (case sensitive)
\? matches the character ? with index 6310 (3F16 or 778) literally (case sensitive)
Non-capturing group
(?:php)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
php
matches the characters php literally (case sensitive)
Non-capturing group
(?:(?!\?>)[\s\S])*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
Negative Lookahead
(?!\?>)
Assert that the Regex below does not match
\? matches the character ? with index 6310 (3F16 or 778) literally (case sensitive)
> matches the character > with index 6210 (3E16 or 768) literally (case sensitive)
Match a single character present in the list below
[\s\S]
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
\S matches any non-whitespace character (equivalent to [^\r\n\t\f\v ])
Non-capturing group
(?:\?>)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
\? matches the character ? with index 6310 (3F16 or 778) literally (case sensitive)
> matches the character > with index 6210 (3E16 or 768) literally (case sensitive)
Global pattern flags
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
x modifier: extended. Spaces and text after a # in the pattern are ignored
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

~
~
gmx

Test String