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.
|^||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'|
|n||Exactly two of 'n'|
|n||At least 2 or more of 'n'|
|n||From 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|