Using preg_match to identify a strong password [duplicate]

Answer 1

PHP regex needs regex delimiters also, so use:

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

Answer 2

Adding the + sign to each condition requires that there is at least one character of this format :

$pattern = '/^(?=.*\d+)(?=.*\W+)(?=.*[A-Z]+)(?=.*[a-z]+)[a-zA-Z\d\W]{8,}$';

and test here : https://regex101.com/r/mSWcPK/1/

Answer 3

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