Item |
Purpose |
\ |
Either begins a special symbol such as \n or escapes the following character |
^ |
Matches the beginning of string (or line if in multiline mode) |
$ |
Matches the end of string (or line if in multiline mode) |
\A |
Matches the beginning of string (even if in multiline mode) |
\Z |
Matches the end of string (even if in multiline mode) |
* |
Matches the preceding character zero or more times |
+ |
Matches the preceding character one or more times |
? |
Matches the preceding character zero or one time |
. |
Matches any character |
[abc] |
Matches any one of the characters inside the brackets |
[^abc] |
Matches one character that is not inside the brackets |
[a-z] |
Matches one character in the range of characters |
[^a-z] |
Matches one character that is not in the range of characters |
x|y |
Matches x or y |
(pattern) |
Makes a match group |
(?<name>pattern) |
Makes a match group and gives it a name |
\n |
Refers to a previously defined group |
(?:pattern) |
Make a non-capturing group (a group that you can't later refer to) |
{n} |
Matches exactly n occurrences |
{n,} |
Matches n or more occurrences |
{n,m} |
Matches between n and m occurrences |
(?=...) |
Positive lookahead (must match the pattern at this point) |
(?!...) |
Negative lookahead (must not match the pattern at this point) |
(?<=...) |
Positive lookbehind (the preceding text must match the pattern) |
(?<!--...) |
Negative lookbehind (the preceding text must not match the pattern) |
\b |
Matches a word boundary |
\B |
Matches a non-word boundary |
\d |
Matches a digit |
\D |
Matches a non-digit |
\f |
Matches a form-feed |
\n |
Matches a newline |
\r |
Matches a carriage return |
\s |
Matches white space (space, tab, form-feed, etc.) |
\S |
Matches non-white space |
\t |
Matches a tab |
\v |
Matches a vertical tab |
\w |
Matches a word character (includes underscore) |
\W |
Matches a non-word character |