Expression | Matches |
abc | abc (the exact character sequence, but anywhere in the string) |
^abc | abc at the beginning of the string |
abc$ | abc at the end of the string |
a|b | Either a or b |
^abc|abc$ | abc at either the beginning or the end of the string |
ab{2,4}c | a followed by two, three or four b characters, followed by c |
ab{2,}c | a followed by at least two “b”s followed by a “c” |
ab*c | a followed by any number (zero or more) of “b”s followed by a “c” |
ab+c | a followed by one or more b's followed by a c |
ab?c | a followed by an optional “b” followed by a” c”; that is, either “abc” or “ac” |
a.c | a followed by any single character (not newline) followed by a “c” |
a\.c | a.c |
[abc] | Any one of a, b or c |
[Aa]bc | Either Abc or abc |
[abc]+ | Any combination of one or more a, b, and/or c characters (such as a, abba, or acbabcacaa) |
[^abc]+ | Any combination of one or more characters that does not contain an a, b, and/or c (such as defg) |
\d\d | Any two decimal digits, such as 42; same as \d{2} |
\w+ | A word (a non-empty sequence of alphanumeric characters and underscores), such as foo, 12bar8, or foo_1 |
100\s*mk | 100 and mk separated by zero or more white space characters (spaces, tabs, newlines) |
abc\b | abc when followed by a word boundary (for example, abc! but not abcd) |
start\B | start when not followed by a word boundary (for example, starting but not start time) |
\x | Ignores white space that is neither preceded by a backslash character nor within a character class. Use this to break up a regular expression into (slightly) more readable parts. |
/x | Used to add regular expressions within other text. If the first character in a pattern is forward slash (/), the / is treated as the delimiter. The pattern must contain a second /. The pattern between / will be taken as a regular expression, and anything after the second / will be parsed as a list of regular expression options (i, x, etc). An error occurs If the second / is missing. In regular expressions, the leading and trailing space is treated as part of the regular expression. |