Check password length in php

I have written function to check password length in php

<?php
$password="checkpassword";


$passwordCheck=passwordLength($passwod);


function passwordLength($pwd)
{
    $pwdlen=strlen($pwd);//calculate length of password using strlen function


      if($pwdlen<=4) //if length of password is less than 4 then password is too short.
      {
         return "Password too short!";
      }
    else if ($pwdlen>16) //if length of password is greater than 16 then password is too Long.
   {
         return "Password too Long!";
     }
} 


?>