PHP密码检查器

I have written a password checker using PHP and It worked fine. It consists of many "if else". Is there any way to minimize my usage of "if else" in my code?

function passtest($pass) {
            if (!empty($pass)) { //check if string is empty
                if (ctype_alnum($pass)) { //check if string is alphanumeric
                    if (7 < strlen($pass)){ //check if string meets 8 or more characters
                        if (strcspn($pass, '0123456789') != strlen($pass)){ //check if string has numbers
                            if (strcspn($pass, 'abcdefghijklmnopqrstuvwxyz') != strlen($pass)) { //check if string has small letters
                                if (strcspn($pass, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ') != strlen($pass)) { //check if string has capital letters
                                    return "<br />Password passed";
                                }
                                else {
                                    return "<br />No capital letter";
                                }
                            }
                            else {
                                return "<br />No small letter";
                            }
                        }
                        else {
                            return "<br />No number";
                        }
                    }
                    else {
                        return "<br />Password is short";
                    }
                }
                else {
                    return "<br />Password has special character";
                }
            }
            else {
                return "<br />Password field is empty";
            }
        }

> xkcd

Your function should just test to see if a password was entered. Other than that, it is not your place to tell people what they can and can't use for a password. How long would it take for a hacker to realise my password is Pokémon, for example? That special character is a HUGE entropy booster.

That aside, to actually answer your question, try formulating your statements in the negative:

if( empty($pass)) return "<br />Password field is empty";
if( !ctype_alnum($pass)) return "<br />Password has special character":
// ...

This has the handy side-effect of keeping the error messages next to the condition they represent.

Use the if elseif else statement.

function passtest($pass) {   
  if (empty($pass)){ //check if string is empty
    return "<br />Password field is empty";
  }elseif (!ctype_alnum($pass)){ //check if string is alphanumeric
    return "<br />Password has special character";
  }elseif (strlen($pass) < 8) { //check if string meets 8 or more characters
    return "<br />Password is short";
  }elseif (strspn($pass, '0123456789') != strlen($pass)){ //check if string has numbers
    return "<br />No number";
  }elseif (strspn($pass, 'abcdefghijklmnopqrstuvwxyz') != strlen($pass)) { //check if string has small letters
    return "<br />No small letter";
  }elseif (strspn($pass, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ') != strlen($pass)) { //check if string has capital letters
    return "<br />No capital letter";
  }else{
    return "<br />Password passed";
  }
}

If your concerned with using if else statements and not concerned with readability you could avoid them all together..

function passtest($pass) {
    return !empty($pass) ? ctype_alnum($pass) ? 7 < strlen($pass) ? strcspn($pass, '0123456789') != strlen($pass) ? strcspn($pass, 'abcdefghijklmnopqrstuvwxyz') != strlen($pass) ? strcspn($pass, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ') != strlen($pass) ? "<br />Password passed" : "<br />No capital letter" : "<br />No small letter" : "<br />No number" : "<br />Password is short" : "<br />Password has special character" : "<br />Password field is empty";
}