Regular Expressions 101

Pro

Group NAME(?P<NAME>pattern1)?

?repeats the group contents below at most once:

pattern1the literal text pattern1 (case sensitive)

Group NAME(?P<NAME>pattern2)?

?repeats the group contents below at most once:

pattern2the literal text pattern2 (case sensitive)

(?P>NAME)?optionally calls group NAME as a subroutine

\sany whitespace character

(?P>NAME)calls group NAME as a subroutine

$end of line

Global pattern flags

J modifier: Allow duplicate subpattern names

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

g modifier: global. Finds all matches instead of stopping after the first

Detailed match information will be displayed here automatically.

25 tokens

Regular Expression

(?P<NAME>pattern1)?(?P<NAME>pattern2)?(?P>NAME)?\s(?P>NAME)$

New

# Doesn't match
pattern2

# Doesn't match
pattern1 pattern2

# Doesn't match
pattern2 pattern2

# Matches (uses (?P<NAME>pattern1) instead of (?P<NAME>pattern2))
pattern1 pattern1

# Matches (again uses (?P<NAME>pattern1) instead of (?P<NAME>pattern2))
pattern1pattern2 pattern1