A regular expression that checks for the existence of at least 3 different characters in a string

Question

I need a regular expression that ensures that the string contains at least 3 different characters (of any type).

Example: aqaqaq is invalid because it consists of only two different characters. aqwaqa or aq3aqa or aq! aqa.

Is this possible in regular expression?

Languages: Javascript / PHP

thank

+3

mspir May 04 '12 at 8:01

1 answer

Mark byers · Accepted Answer · 2012-05-04T08:08:53+0000

You can use this regex containing negative images:

/(.).*(?!\1)(.).*(?!\1)(?!\2)(.)/

Examples:

> regex = /(.).*(?!\1)(.).*(?!\1)(?!\2)(.)/
> regex.exec('abab!aba')
["abab!ab", "a", "!", "b"]
> regex.exec('abababa')
null