Question

i have this strange problem with the PHP function CTYPE_ALNUM

if i do:

PHP:

$words="àòè";


if(ctype_alnum($words)){

   Echo "Don't work";

}else{

   Echo "Work";     

}

this will echo out ‘Work’

BUT if i have a form and in that form i insert the letters with the grave like (à , è, ò) this will echo out ‘Don’t Work’

Code:

  <form action="" method="post"> 

    <input type="text" name="words" />
    <input type="submit" />

  </form>


 $words=$_POST['words'];

 if(isset($words)){

  if(ctype_alnum($words)){

      Echo "Don't Work";

  }else{

      Echo "Work";      

 }

}

If i insert into the text input the letters à or è or ò This will echo out ‘Don’t Work’

Answer 1

ctype_alnum is locale-dependend. That means if you’re using the standard C locale or a common one like en_US, that won’t match accented letters, only [A-Za-z]. You can try setting the locale to a language that recognizes those derivations via setlocale (beware that the locale needs to be installed on your system, and not all systems are alike), or use a more portable solution like:

function ctype_alnum_portable($text) {
    return (preg_match('~^[0-9a-z]*$~iu', $text) > 0);
}