can't understand this function from php manual example (return bytes)


I've seen this function in the php manual but I can't understand how it works , the function is supposed to change the value of file size into bytes. this is the whole example

Our php.ini contains the following settings:

display_errors = On
register_globals = Off
post_max_size = 8M

echo 'display_errors = ' . ini_get('display_errors') . "\n";
echo 'register_globals = ' . ini_get('register_globals') . "\n";
echo 'post_max_size = ' . ini_get('post_max_size') . "\n";
echo 'post_max_size+1 = ' . (ini_get('post_max_size')+1) . "\n";
echo 'post_max_size in bytes = ' . return_bytes(ini_get('post_max_size'));

function return_bytes($val) {
    $val = trim($val);
    $last = strtolower($val[strlen($val)-1]);
    switch($last) {
        // The 'G' modifier is available since PHP 5.1.0
        case 'g':
            $val *= 1024;
        case 'm':
            $val *= 1024;
        case 'k':
            $val *= 1024;

    return $val;


what I can't understand is this line

$last = strtolower($val[strlen($val)-1]);

and that what called 'G' modifier , and what is $last variable used for? Thanks in advance ,




$last = strtolower($val[strlen($val)-1]);

That line of code is getting the last character in$val, converting it to lower case, then putting it in the$last variable. That variable is then used in the switch statement to apply a multiplier to the input value.

See for some background information that might be useful to you.

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