Using preg_match to identify a strong password [duplicate]

Question

I had thought to use preg_match() to check if a password is correctly entered. I want at least 1 uppercase letter, at least 1 lowercase letter, at least one number, and at least one special char. Here's what I am using:

$pattern = "(?=^.{8,}$)((?=.*\d)|(?=.*\W+))(?![.\n])(?=.*[A-Z])(?=.*[a-z]).*$";

This regex is working fine in HTML's "pattern" field. But I need to ensure that it's also verified for older browsers.

My PHP code is this:

if (!(preg_match($pattern, $loginpassword))) {echo "Password must include one uppercase letter, one lowercase letter, one number, and one special character such as $ or %."; die;}

I thought it was working great except when I use the password 1@abcdeF it also fails to match. The php code seems to work but no password ever matches, even when it SHOULD fit the pattern. HTML5 will let it through so I suspect the regex statement is correct, but something about my setup in PHP is flawed. Can anyone see what I'm missing?

Answer 1

Use the following pattern:

$strong_password = preg_match('/^(?=.[a-z])(?=.[A-Z])(?=.\d)(?=.[^A-Za-z\d])[\s\S]{6,16}$/', $string);

^                 --> start of string

(?=.*[a-z])       --> at least one lowercase letter 

(?=.*[A-Z])       --> at least one uppercase letter 

(?=.*\d)          --> at least one number 

(?=.*[^A-Za-z\d]) --> at least one special character

[\s\S]{6,16}      --> total length between 6 and 16

$                 --> end of string