PHP intercepts Chinese function utf_substr

$tmp = preg_replace('/[一-龥]/u','<@>','Hello who am I? 123abc');
/u is UTF-8

Code 1, PHP intercepts UTF-8 strings to solve the half-character problem

/***
* PHP intercepts UTF-8 strings and solves the half-character problem. utf_substr
* English and numbers (half-width) are 1 byte (8 bits), Chinese (full-width) are 3 bytes
* @return When $len is less than or equal to 0, the entire string will be returned
* @param $str Source string
* $len The length of the substring on the left
* @edit bbs.it-home.org
function utf_substr($str,$len){
for($i=0;$i< $len;$i++){
 $temp_str=substr($str,0,1);
 if(ord($temp_str) > 127){
 $i++;
 if($i<$len){
 $ new_str[]=substr($str,0,3);
 $str=substr($str,3);
 }
 }else{
 $new_str[]=substr($str,0,1);
 $ str=substr($str,1);
 }
}
return join($new_str);
}
//Calling example
$str = utf_substr('Hello',4 );
echo $str;
?>

Code 2, intercept utf-8 string function

/**
* Intercept utf-8 string
* edit bbs.it-home.org
*/
function cut_str($sourcestr,$cutlength){
$returnstr='';
$i=0;
$ n=0;
$str_length=strlen($sourcestr);//The number of bytes in the string
while (($n<$cutlength) and ($i<=$str_length)){
 $temp_str=substr($ sourcestr,$i,1);
 $ascnum=Ord($temp_str);//Get the ascii code of the $i-th character in the string
 if ($ascnum>=224){ //If the ASCII bit is high and 224 ,
 $returnstr=$returnstr.substr($sourcestr,$i,3); //According to the UTF-8 encoding specification, 3 consecutive characters are counted as a single character
 $i=$i+3; //Actual Byte is counted as 3
 $n++; //String length is counted as 1
 }elseif ($ascnum>=192){ //If the ASCII bit is higher than 192,
 $returnstr=$returnstr.substr($sourcestr,$i, 2); //According to the UTF-8 encoding specification, 2 consecutive characters are counted as a single character
 $i=$i+2; //The actual Byte is counted as 2
 $n++; //The string length is counted as 1
 }elseif ($ascnum>=65 && $ascnum<=90){ //If it is an uppercase letter,
 $returnstr=$returnstr.substr($sourcestr,$i,1);
 $i=$i+1; //The actual Byte number is still counted as 1
 $n++; //But considering the overall aesthetics, uppercase letters are counted as one high-bit character
 }else{ //In other cases, including lowercase letters and half-width punctuation marks,
 $returnstr= $returnstr.substr($sourcestr,$i,1);
 $i=$i+1; //The actual Byte count is 1
 $n=$n+0.5; //Lowercase letters and half-width punctuation are equal to Half the high character width...
 }
}
if ($str_length>$cutlength){
 $returnstr = $returnstr . "...";//Add an ellipse at the end when the length exceeds
}
return $returnstr;
}
//Call example
$str = 'Hello! I'm good';
$str = cut_str($str,3);
echo $str;
? >