PCRE Characters
Ranges
. |
any single character |
[abc] |
a single character of: a, b or c |
[^abc] |
any single character except: a, b, or c |
[a-z] |
any single character in the range a-z |
[a-zA-Z] |
any single character in the range a-z or A-Z |
Assertions
^ |
start of line |
$ |
end of line |
\b |
any word boundary character |
\B |
any non-word boundary character |
\A |
start of string |
\z |
end of string |
PCRE Controls
Quantifiers
(a|b) |
a or b |
a? |
zero or one of a |
a* |
zero or more of a |
a+ |
one or more of a |
a{3} |
exactly 3 of a |
a{3,} |
3 or more of a |
a{3,6} |
between 3 and 6 of a |
Subpattern modifiers
foo(?=bar) |
foo will match if it's followed by bar |
foo(?!bar) |
foo will match if it's not followed by bar |
(?<=foo)bar |
bar will match if it's preceded by foo |
(?<!foo)bar |
bar will match if there isn't a foo behind it |
(foo)?(?(1)(bar)) |
bar will be captured only if foo was |
PCRE Character Classes
Generic character types
\s |
any whitespace character |
\S |
any non-whitespace character |
\d |
any digit |
\D |
any non-digit |
\w |
any word character (letter, number, underscore) |
\W |
any non-word character |
POSIX Classes
[:alnum:] |
letters and digits |
[:alpha:] |
letters |
[:ascii:] |
character codes 0 - 127 |
[:blank:] |
space or tab only |
[:cntrl:] |
control characters |
[:graph:] |
printing characters, excluding space |
[:print:] |
printing characters, excluding space |
[:punct:] |
printing characters, excluding letters and digits and spaces |
[:space:] |
white space (not quite the same as \s) |
[:xdigit:] |
hexadecimal digits |
Usage examples
POSIX classes are supported only as sub-classes
([] define a class);
to match hexadecimal digits
along with the characters % and }:
[%{[:xdigit:]]
To negate a class, prefix the identifier with ^:
[%{[:^xdigit:]]
