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
/
(?|^(\d)|\D(\d))(?!\d)
/
gm
Branch Reset Group
(?|^(\d)|\D(\d))
Subpatterns declared within each alternative of this construct will start over from the same index.
1st Alternative
^(\d)
^ asserts position at start of a line
1st Capturing Group
(\d)
\d matches a digit (equivalent to [0-9])
2nd Alternative
\D(\d)
\D matches any character that's not a digit (equivalent to [^0-9])
1st Capturing Group
(\d)
\d matches a digit (equivalent to [0-9])
Negative Lookahead
(?!\d)
Assert that the Regex below does not match
\d matches a digit (equivalent to [0-9])
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)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
gm

Test String

Code Generator

Generated Code

Loading code sample...
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report.
For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php