PHP Chinese encoding judgment code

preg_replace(”/([x80-xff])/”,””,$str);
preg_replace(”/([u4e00-u9fa5])/”,””,$str);

Example, PHP Chinese encoding judgment.

//Determine whether there is Chinese in the content-gbk (php)
function check_is_chinese($s){
return preg_match('/[x80-xff]./', $s) ;
}
//Get the string length-gbk (php)
function gb_strlen($str){
$count = 0;
for($i=0; $i$s = substr($str, $i, 1);
if (preg_match("/[x80-xff]/", $s)) ++$i;
++$count;
}
return $ count;
}
//Intercept string string-gbk (php)
function gb_substr($str, $len){
$count = 0;
for($i=0; $iif($count == $len) break;
if(preg_match("/[x80-xff]/", substr($str, $i, 1))) ++$i;
 ++$count;
}
return substr($str, 0, $i);
}
//Statistical string length-utf8 (php)
function utf8_strlen($str) {
$count = 0;
for ($i = 0; $i < strlen($str); $i++){
$value = ord($str[$i]);
if($value > 127) {
$count++;
if ($value >= 192 && $value <= 223) $i++;
elseif($value >= 224 && $value <= 239) $i = $i + 2;
elseif($value > = 240 && $value <= 247) $i = $i + 3;
else die('not a utf-8 compatible string');
}
$count++;
}
return $count;
}
/ /Intercept string-utf8(php)
function utf8_substr($str,$position,$length){
$start_position = strlen($str);
$start_byte = 0;
$end_position = strlen($str);
 $count = 0;
for($i = 0; $i < strlen($str); $i++){
if($count >= $position && $start_position > $i){
$start_position = $i;
$start_byte = $count;
}
if(($count-$start_byte)>=$length) {
$end_position = $i;
break;
}
$value = ord($str[ $i]);
if($value > 127){
$count++;
if($value >= 192 && $value <= 223) $i++;
elseif($value >= 224 && $ value <= 239) $i = $i + 2;
elseif($value >= 240 && $value <= 247) $i = $i + 3;
else die('not a utf-8 compatible string');
}
$count++;
}
return(substr($str,$start_position,$end_position-$start_position));
}
//Determine whether there is Korean-utf-8 (javascript)
function checkkoreachar(str) {
for(i=0; iif(((str.charcodeat(i) > 0x3130 && str.charcodeat(i) < 0x318f) || (str .charcodeat(i) >= 0xac00 && str.charcodeat(i) <= 0xd7a3))) {
return true;
}
}
return false;
}
//Determine whether there are Chinese characters-gbk (javascript )
function check_chinese_char(s){
return (s.length != s.replace(/[^x00-xff]/g,"**").length);
}