The implementation of escape decoding function in PHP

 
function unescape($str) { 
$str = rawurldecode($str); 
preg_match_all("/%u.{4}|&#x.{4};|&#d+;|.+/U",$str,$r); 
$ar = $r[0]; 
foreach($ar as $k=>$v) { 
if(substr($v,0,2) == "%u") 
$ar[$k] = iconv("UCS-2","GBK",pack("H4",substr($v,-4))); 
elseif(substr($v,0,3) == "&#x") 
$ar[$k] = iconv("UCS-2","GBK",pack("H4",substr($v,3,-1))); 
elseif(substr($v,0,2) == "&#") { 
$ar[$k] = iconv("UCS-2","GBK",pack("n",substr($v,2,-1))); 
} 
} 
return join("",$ar); 
} 

 
function unescape($str){ 
$ret = ''; 
$len = strlen($str); 
for ($i = 0; $i < $len; $i++){ 
if ($str[$i] == '%' && $str[$i+1] == 'u'){ 
$val = hexdec(substr($str, $i+2, 4)); 
if ($val < 0x7f) $ret .= chr($val); 
else if($val < 0x800) $ret .= chr(0xc0|($val>>6)).chr(0x80|($val&0x3f)); 
else $ret .= chr(0xe0|($val>>12)).chr(0x80|(($val>>6)&0x3f)).chr(0x80|($val&0x3f)); 
$i += 5; 
} 
else if ($str[$i] == '%'){ 
$ret .= urldecode(substr($str, $i, 3)); 
$i += 2; 
} 
else $ret .= $str[$i]; 
} 
return $ret; 
}