Regular Expressions Help
Note: The RegEx Lab makes use of PCRE, i.e., Perl Compatible Regular Expressions. You can read more about it here.
Meta characters
\
general escape character with several uses
^
assert start of subject (or line, in multiline mode)
$
assert end of subject (or line, in multiline mode)
.
match any character except newline (by default)
[
start character class definition
]
end character class definition
|
start of alternative branch
(
start subpattern
)
end subpattern
?
extends the meaning of (, also 0 or 1 quantifier, also quantifier minimizer
*
0 or more quantifier
+
1 or more quantifier
{
start min/max quantifier
}
end min/max quantifier
Part of a pattern that is in square brackets is called a "character class". In a character class the only meta-characters are:
\
general escape character
^
negate the class, but only if the first character
-
indicates character range
]
terminates the character class