Metacharacters
General information about metacharacters.
Any single character (letter, digit, or symbol) in a regular expression is matched to itself, literally; unless it is a metacharacter. A metacharacter is one or more characters that have a unique meaning and are not used literally in the regular expression match.
For example, the circumflex character (^) is a metacharacter that means "search at the beginning".
If you want to find the character, rather than the metacharacter pattern, put a backslash (\) before it.
For example, to find the circumflex as a text character, the regular expression must be: \^
Reg. Exp. |
Description |
Example |
---|---|---|
\ |
Find the next character as a character; do not use its metacharacter pattern. |
\. finds a period (.) in the text . finds the first character (any character) |
^ |
Find at the beginning of a string |
^1 finds "1. Click Save." but not: "in the 210th line" |
. |
Find any character (except newline). |
Finds a, A, 1, <, ., =, and so on; whatever the first character is. |
() |
Find a pattern group. |
(word) finds "In this word" ^(Word) finds "Words in this line" |
[] |
Find a pattern range. |
[a-z] finds letters, but not numbers |
* |
Find the previous pattern zero or more times. |
.* finds all characters <(.*)> finds all HTML tags |
+ |
Finds the previous pattern one or more times. |
(<.l>)+ finds <UL><OL> |
? |
Finds the previous pattern zero or one time. |
(<.l>)? finds <UL> |
(?i) |
Find the next characters with a case-insensitive search. |
(?i)word finds word and Word |