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
/
\\n(.*?(?:\\n|$))
/
gm
\\ matches the character \ with index 9210 (5C16 or 1348) literally (case sensitive)
n matches the character n with index 11010 (6E16 or 1568) literally (case sensitive)
1st Capturing Group
(.*?(?:\\n|$))
.
matches any character (except for line terminators)
*? matches the previous token between zero and unlimited times, as few times as possible, expanding as needed (lazy)
Non-capturing group
(?:\\n|$)
1st Alternative
\\n
\\ matches the character \ with index 9210 (5C16 or 1348) literally (case sensitive)
n matches the character n with index 11010 (6E16 or 1568) literally (case sensitive)
2nd Alternative
$
$ asserts position at the end of a line
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

Substitution

Processing...