| ^Matches beginning of line. |
| $Matches end of line. |
| .Matches any single character except newline. Using m option allows it to match newline as well. |
| [...]Matches any single character in brackets. |
| [^...]Matches any single character not in brackets |
| re*Matches 0 or more occurrences of preceding expression. |
| re+Matches 1 or more occurrence of preceding expression. |
| re?Matches 0 or 1 occurrence of preceding expression. |
| re{ n}Matches exactly n number of occurrences of preceding expression. |
| re{ n,}Matches n or more occurrences of preceding expression. |
| re{ n, m}Matches at least n and at most m occurrences of preceding expression. |
| **a\ |
b**Matches either a or b. |
| (re)Groups regular expressions and remembers matched text. |
| (?imx)Temporarily toggles on i, m, or x options within a regular expression. If in parentheses, only that area is affected. |
| (?-imx)Temporarily toggles off i, m, or x options within a regular expression. If in parentheses, only that area is affected. |
| (?: re)Groups regular expressions without remembering matched text. |
| (?imx: re)Temporarily toggles on i, m, or x options within parentheses. |
| (?-imx: re)Temporarily toggles off i, m, or x options within parentheses. |
| (?#...)Comment. |
| (?= re)Specifies position using a pattern. Doesn't have a range. |
| (?! re)Specifies position using pattern negation. Doesn't have a range. |
| (?> re)Matches independent pattern without backtracking. |
| \wMatches word characters. |
| \WMatches nonword characters. |
| \sMatches whitespace. Equivalent to [\t\n\r\f]. |
| \SMatches nonwhitespace. |
| \dMatches digits. Equivalent to [0-9]. |
| \DMatches nondigits. |
| \AMatches beginning of string. |
| \ZMatches end of string. If a newline exists, it matches just before newline. |
| \zMatches end of string. |
| \GMatches point where last match finished. |
| \bMatches word boundaries when outside brackets. Matches backspace (0x08) when inside brackets. |
| \BMatches nonword boundaries. |
| \n, \t, etc.Matches newlines, carriage returns, tabs, etc. |
| \1...\9Matches nth grouped subexpression. |
| \10Matches nth grouped subexpression if it matched already. Otherwise refers to the octal representation of a character code. |