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
"
(?:https?:?\/?\/?)?(\d+)[\.:](\d+)[\.:](\d+)[\.:](\d+)(?::\d+)?
"
g
Non-capturing group
(?:https?:?\/?\/?)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
http
matches the characters http literally (case sensitive)
s
matches the character s with index 11510 (7316 or 1638) literally (case sensitive)
:
matches the character : with index 5810 (3A16 or 728) literally (case sensitive)
\/
matches the character / with index 4710 (2F16 or 578) literally (case sensitive)
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
\/
matches the character / with index 4710 (2F16 or 578) literally (case sensitive)
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
1st Capturing Group
(\d+)
\d
matches a digit (equivalent to [0-9])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
Match a single character present in the list below
[\.:]
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
: matches the character : with index 5810 (3A16 or 728) literally (case sensitive)
2nd Capturing Group
(\d+)
\d
matches a digit (equivalent to [0-9])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
Match a single character present in the list below
[\.:]
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
: matches the character : with index 5810 (3A16 or 728) literally (case sensitive)
3rd Capturing Group
(\d+)
\d
matches a digit (equivalent to [0-9])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
Match a single character present in the list below
[\.:]
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
: matches the character : with index 5810 (3A16 or 728) literally (case sensitive)
4th Capturing Group
(\d+)
\d
matches a digit (equivalent to [0-9])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
Non-capturing group
(?::\d+)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
: matches the character : with index 5810 (3A16 or 728) literally (case sensitive)
\d
matches a digit (equivalent to [0-9])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
Global pattern flags
g modifier: global. All matches (don't return after first match)
Your regular expression does not match the subject string.

Regular Expression
No Match

r"
"
g

Test String