Regular Expressions / Regex Cheat Sheet

Special Characters in Regular Expressions & their meanings

Character Meaning Example
* Match zero, one or more of the previous Ah* matches "Ahhhhh" or "A"
? Match zero or one of the previous Ah? matches "Al" or "Ah"
+ Match one or more of the previous Ah+ matches "Ah" or "Ahhh" but not "A"
\ Used to escape a special character Hungry\? matches "Hungry?"
. Wildcard character, matches any character do.* matches "dog", "door", "dot", etc.
( ) Group characters See example for |
[ ] Matches a range of characters [cbf]ar matches "car", "bar", or "far"
[0-9]+ matches any positive integer
[a-zA-Z] matches ascii letters a-z (uppercase and lower case)
[^0-9] matches any character not 0-9.
| Matche previous OR next character/group (Mon|Tues)day matches "Monday" or "Tuesday"
{ } Matches a specified number of occurrences of the previous [0-9]{3} matches "315" but not "31"
[0-9]{2,4} matches "12", "123", and "1234"
[0-9]{2,} matches "1234567..."
^ Beginning of a string. Or within a character range [] negation. ^http matches strings that begin with http, such as a url.
[^0-9] matches any character not 0-9.
$ End of a string. ing$ matches "exciting" but not "ingenious"