Concatenating Strings

The error message in stringlength.php is not really helpful for the user so you need to give more information to help them.  Save it as stringjoin.php and change the die line to this:

die("Password too short, your password is $passwordLength but it needs to be at least $minimumPasswordLength.");

Try it.  The PHP server has combined the variable text with the actual text.  This is known as concatenation.  The following code does concatenation as well but in a slightly different way (for information only):

$errorMessage="Password too short, your password is ".$passwordLength." but it needs to be at least ".$minimumPasswordLength.".";
die($errorMessage);

That method is used in JavaScript and many other languages (including PHP) but the way used in your code looks much neater.