Example: Check Usernames

Oilik · 07-27-2008, 06:29 PM

This is a simple function I made to check if a string is a valid username or not. If it has illegal characters not specified, it'll return false/nothing, and if it's valid it'll return true/1.

PHP Code:


			
<?php

function isValid($string){

    $string = str_replace("_","",$string);

    $string = str_replace(" ","",$string);

    $string = str_replace(".","",$string);

    $string = str_replace("-","",$string);

        if(ctype_alnum($string)){

            return true;

        }else{

            return false;

        }

}

?>

This is easier to remember than preg_replace for me :(
I've never quite understood that function...

delayedinsanity · 07-27-2008, 08:45 PM

PHP Code:


			
return preg_match('~^[A-Za-z][A-Za-z0-9_]{3,29}$~', $szString) ? TRUE : FALSE;

Username must be between 4 to 30 characters in length, may contain letters, numbers or underscores, but must start with a letter.
-m

Oilik · 07-27-2008, 08:47 PM

Quote:

Originally Posted by delayedinsanity

PHP Code:


			
return preg_match('~^[A-Za-z][A-Za-z0-9_]{3,29}$~', $szString) ? TRUE : FALSE;

Username must be between 4 to 30 characters in length, may contain letters, numbers or underscores, but must start with a letter.
-m

Woah.. Thanks, thats useful. Intense too. :P

sketchMedia · 08-07-2008, 11:32 AM

I think that could be further condensed:

PHP Code:


			
return preg_match('/^[a-z][\w]{3,29}$/i', $szString) ? true : false;

'\w' stands for "word character" and is the same as [A-Za-z0-9_](including underscores)
and the 'i' at the end of the expression (after the trailing '/') makes it case insensitive.
If you want to enforce a capital at the start of the username just remove the 'i' and change the '[a-z]' to '[A-Z]' or vice-versa

To actually strip the chars specified in your function from the string with preg_replace:

PHP Code:


			
echo preg_replace('/[_.-\s]/', '$1', $szString);

should do it