Regular Expression Tester

Anytime I use regular expressions (aka "regex"), I find myself doing a bit of trial-and-error until I get the right pattern. So, I whipped up this simple utility to help.

The tool will tell you where, if any, the patten is matched in your string by replacing any matching parts with [!MATCH!], and will point out parenthesized substrings.

If you're new to regexes, a good book to check out is Mastering Regular Expressions.

Pattern:
Haystack:
Type: preg (PCRE) ereg (POSIX)

Helpful Hints

^Start of String
$End of string
\Escape the next character; interpret it literally
n*Zero or more of 'n'
n+One or more of 'n'
n?A possible 'n'
nExactly two of 'n'
nAt least 2 or more of 'n'
nFrom 2 to 4 of 'n'
()Parenthesis to group substrings
(n|a)Either 'n' or 'a'
.Any single character
[1-6]A number between 1 and 6
[c-h]A lower case character between c and h
[D-M]An upper case character between D and M
[^a-z]Absence of lower case a to z
[_a-zA-Z]An underscore or any letter of the alpha