刷题记录-ASCII码 （转字符串）

题目：转换以下ASCII码为对应字符并输出他们。
73, 32, 99, 97, 110, 32, 100, 111, 32, 105, 116 , 33

注意，当数值少于128，原样输出。

以下代码参考了网上一个PHP实现ASCII码与字符串转换的写法。（https://www.jb51.net/article/112523.htm ）

<?php
class ascii{
    function decode($str,$prefix="&#"){
        $str = str_replace($prefix,"",$str);
        $a = explode(";",$str);
        foreach($a as $dec){
            if ($dec < 128){
                $utf .= chr($dec);
            } elseif ($dec < 2048){
                $utf .= chr(192 + (($dec - ($dec%64)) / 64));
                $utf .= chr(128 + ($dec % 64));
            } else {
                $utf .= chr(224 + (($dec - ($dec % 4096)) / 4096));
                $utf .= chr(128 + ((($dec % 4096) - ($dec % 64)) / 64));
                $utf .= chr(128 + ($dec % 64));
            }
        }
        return $utf;
    }
}

$exc = new ascii;
print($exc->decode('73'));
print($exc->decode('32'));
print($exc->decode('99'));
print($exc->decode('97'));
print($exc->decode('110'));
print($exc->decode('32'));
print($exc->decode('100'));
print($exc->decode('111'));
print($exc->decode('32'));
print($exc->decode('105'));
print($exc->decode('116'));
print($exc->decode('33'));