We often see an error message "Username must be between 5 to 10 characters" displayed on a site while registering for an account.Do you know how to put this feature on your website.Yes,you can and its just a 1 minute game.We use a string function "strlen" to find the length of a string.So we apply this here in our script.

if( strlen($username) <6 || strlen($username) >12)
{
print "Username must be between 6 to 12 characters!";
}

Perhaps you can apply some more security on this script.You can also apply this script on the password textbox.