减少php中的字母值[关闭]

Question

Base on the answer Decrementing alphabetical values

what about if i have a character like this $char='AF', how can i make it to $char='AE' and so on ?

UPDATE

Here is my complete solution:

function decrementChar($par){
    if(strlen($par)>=2){
        $str= substr($par,0,-1); 
        $strdec= substr($par,-1);           
        $strdec=$strdec=='A'?'':chr(ord($strdec) - 1 );
        return $str.$strdec;
    }
    return chr(ord($par) - 1 );

}

Answer 1

if your string is a hex value, you can use the following code:

$char = 'AF';
$value = hexdec($char);
$value--;
$char = dechex($value);

if you string is just a string:

$len = strlen($char);
$char[$len - 1] = chr(ord($char[$len - 1]) - 1);