Does strtoupper work with letters and numbers

I have a short line of code that I would like to make uppercase.

$box = mysql_real_escape_string(strtoupper($_POST['box']));

For some reason, it is not making it u开发者_运维问答ppercase. Could it be because the post is a mixture of letters and numbers? ie; ee588. Thanks

You can also try to use mb_strtoupper($str, 'UTF-8');. This accept the encoding. Maybe you are having not exactly the letter 'e' like you know.

Link to manual: mb_strtoupper()

this works:

echo strtoupper('ee588');

you should check that the 'ee' you see is correctly encoded
you can test it here

Check your locale settings. Strtoupper is locale-dependent