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
/
([\d:\.]*?)\s+?(\d+?)\s+?([\d:\.]*?)\s+?(\d+?)\s+?(\d+?)\n
/
gm
1st Capturing Group
([\d:\.]*?)
Match a single character present in the list below
[\d:\.]
*? matches the previous token between zero and unlimited times, as few times as possible, expanding as needed (lazy)
\d matches a digit (equivalent to [0-9])
: matches the character : with index 5810 (3A16 or 728) literally (case sensitive)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
+? matches the previous token between one and unlimited times, as few times as possible, expanding as needed (lazy)
2nd Capturing Group
(\d+?)
\d
matches a digit (equivalent to [0-9])
+? matches the previous token between one and unlimited times, as few times as possible, expanding as needed (lazy)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
+? matches the previous token between one and unlimited times, as few times as possible, expanding as needed (lazy)
3rd Capturing Group
([\d:\.]*?)
Match a single character present in the list below
[\d:\.]
*? matches the previous token between zero and unlimited times, as few times as possible, expanding as needed (lazy)
\d matches a digit (equivalent to [0-9])
: matches the character : with index 5810 (3A16 or 728) literally (case sensitive)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
+? matches the previous token between one and unlimited times, as few times as possible, expanding as needed (lazy)
4th Capturing Group
(\d+?)
\d
matches a digit (equivalent to [0-9])
+? matches the previous token between one and unlimited times, as few times as possible, expanding as needed (lazy)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
+? matches the previous token between one and unlimited times, as few times as possible, expanding as needed (lazy)
5th Capturing Group
(\d+?)
\d
matches a digit (equivalent to [0-9])
+? matches the previous token between one and unlimited times, as few times as possible, expanding as needed (lazy)
\n matches a line-feed (newline) character (ASCII 10)
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