Regular Expression
A
| Character | Meaning |
|---|---|
^ |
Matches start of string. |
$ |
Matches end of string. |
. |
Matches any character. |
\ |
Escape character. Causes the next character to have its ordinary meaning.
For example, the regular expression \.. matches .a
and .2 and any other two-character string that begins with a period. |
* |
Matches zero or more instances of the preceding character.
For example, ba* matches b,
ba, baa, etc.
|
+ |
Matches one or more instances of the preceding character.
For example, ba+ matches
ba, baa, etc.
|
[] |
Indicates a set of characters that can match the current character.
A hyphen can be used to indicate a range of characters. For example,
[a-zA-Z0-9_]+ matches foo_bar1 but not
foo$bar. A ^ indicates a match when the
current character is not one of the following characters. For
example, [^0-9] matches any character that is not a digit. |
\w |
Matches a word character (same as [a-z_A-Z0-9]). |
\W |
Matches a nonword character (same as [^a-z_A-Z0-9]). |
\d |
Matches a digit (same as [0-9]). |
\D |
Matches a nondigit (same as [^0-9]). |
\s |
Matches white space (same as [ \t\r\n\f]). |