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
/
^([^\.]+)\.([^\[]+| ?)(.*)
/
^ asserts position at start of the string
1st Capturing Group
([^\.]+)
Match a single character not present in the list below
[^\.]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
2nd Capturing Group
([^\[]+| ?)
1st Alternative
[^\[]+
Match a single character not present in the list below
[^\[]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\[ matches the character [ with index 9110 (5B16 or 1338) literally (case sensitive)
2nd Alternative
?
matches the character with index 3210 (2016 or 408) literally (case sensitive)
3rd Capturing Group
(.*)
.
matches any character (except for line terminators)
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
Your regular expression does not match the subject string.

Regular Expression
No Match

/
/

Test String