Public domain
Patterns of characters that are used in searching databases
| Metacharacter | Meaning | Example | Explanation |
| . | Exactly one character, not null | . | One character, not null. |
| * | zero or more times (like {0,}) | ab*c | ac, abc, abbc, abbbc, ... |
| + | once or more times (like {1,}) | ab+c | abc, abbc, abbbc, ... |
| ? | zero or once (like {0,1}) | ab?c | ac,abc. |
| ^ | Beginning of the line | ^abc | Lines witch begin with "abc". |
| $ | End of the line | abc$ | Lines witch end with "abc". |
| \ | Escape carahcter | \. | dot character. |
| [] | One occurence of list | [abc] | matches a,b or c. |
| [-] | Range of characters | [a-d] | matches a,b,c or d. |
| [^] | Reverse range of characters | [^a-d] | matches not a,b,c or d. |
| (|) | alternative text | (abc|def) | matches abc or def. |
| \d | exactly one digit | \d\d | 00, 01, ..., 99. |
| \D | everything except digit | \D\D | not 00,...,99. |
| \w | exactly one letter,number or underscore (like [A-z0-9_]) | \w | a, 1, _, .... |
| \W | everything except letter, number or underscore(like [^A-z0-9_]) | \W | @,#,... |
| \s | exactly one whitespace (space,tab,newline) | \s | |
| \S | everything except whitespace | \S | @ |
| \b | word boundary | \bdef | def (not abcdef) |
| \B | non-word boundary | \Bdef | abcdef (not def) |
| \t | tab character | ||
| \n | carriage return | ||
| \nnn | octal number | \007 | bell character |
| {m} | character repetitions (m times) | a{2} | aa |
| {m,n} | character repetitions (minimum m, maximum n) | a{2,3} | aa,aaa |
| {m,} | character repetitions (minimum m) | a{2,} | aa,aaa,aaaa,aaaaa,... |
BY: Pejman Moghadam
TAG: regex
DATE: 2009-04-25 00:16:37