preg-match

I have this code that makes sure the username is only letters and numbers but then way my code is set up I need it to check if the preg_match is false. Right now it says "if secure echo this" I need it's logic to say "if not secure say this". Can someone help me out? if (preg_match('/[A-Z]+[a-z]+[0-9]+/', $username)) { echo 'Secure enough'; } You can negate the condition like this: if (!preg_match('/^[A-Za-z0-9]+$/', $username)) { echo 'Secure enough'; } Also, your regex needs to be [A-Za-z0-9]+ if you mean "alphanumeric" (only letters and numbers) as a whole. The regex in your code would

I'd like to use a kind of logical operator "AND" in my regular expression. I tried this: (?=exp1)(?=exp2) But in PHP ?= doesn't work and need to write my program in PHP language. Is there another method? The expression has to match if there are present all the conditions and in any order. I don't wanna write every permutation like: (exp1)(exp2)(exp3)|(exp1)(exp3)(exp2)|.... PHP does support lookahead expressions. You're probably not using them correctly, though. Assuming you want to match a string that contains all three of foo , bar and baz , you need the regex ^(?=.*foo)(?=.*bar)(?=.*baz)