Question

See my post here

Regex for at least 8 + upper and lower+numbers or other non-alphabetic

Suppose i just need this 2 condition below,
what should be the regular expression?

1. Contains upper and lower case letters.
2. Contains numbers or other non-alphabetic characters.

I tried ^(?=.*?[a-z])(?=.*?[A-Z])(?=.*?[^a-zA-Z])$
but not working

BUT just-
–(?=.*?[a-z])(?=.*?[A-Z])(?=.*?[^a-zA-Z]) is working

can i use just (?=.*?[a-z])(?=.*?[A-Z])(?=.*?[^a-zA-Z]) for the purpose?

Answer 1

The problem here is that the look ahead/behind are zero-width, “non-consuming”. That means your

^(?=.*?[a-z])(?=.*?[A-Z])(?=.*?[^a-zA-Z])$

will never match because the lookarounds consumed nothing and whats then left? only ^$ that would match an empty string, but this does not meet your lookahead criterias.

So you should use

^(?=.*?[a-z])(?=.*?[A-Z])(?=.*?[^a-zA-Z]).*$

that .* will consume everything and the look aheads ensure the criterias.

you can also define a length replacing the * with {x,} where x is the minimum amount of characters of the string