PHP method to intercept mixed Chinese and English strings

This article mainly introduces php to intercept Chinese and English mixed strings. Friends who need it can refer to it

php should intercept strings, so there is no need to use substr or mb_substr

//截取想这样的字符串
a李三

Using ASCII

/**
 * 
 * 中英混合的字符串截取
 * @param unknown_type $sourcestr
 * @param unknown_type $cutlength
 */
function assoc_substr($sourcestr, $cutlength) {
   $returnstr = '';
   $i = 0;
   $n = 0;
   $str_length = strlen ( $sourcestr ); //字符串的字节数 
   while ( ($n < $cutlength) and ($i <= $str_length) ) {
    $temp_str = substr ( $sourcestr, $i, 1 );
    $ascnum = Ord ( $temp_str ); //得到字符串中第$i位字符的ascii码 
    if ($ascnum >= 224) {//如果ASCII位高与224，
       $returnstr = $returnstr . substr ( $sourcestr, $i, 3 ); //根据UTF-8编码规范，将3个连续的字符计为单个字符  
       $i = $i + 3; //实际Byte计为3
       $n ++; //字串长度计1
    } elseif ($ascnum >= 192){ //如果ASCII位高与192，
       $returnstr = $returnstr . substr ( $sourcestr, $i, 2 ); //根据UTF-8编码规范，将2个连续的字符计为单个字符 
       $i = $i + 2; //实际Byte计为2
       $n ++; //字串长度计1
    } elseif ($ascnum >= 65 && $ascnum <= 90) {//如果是大写字母，
     $returnstr = $returnstr . substr ( $sourcestr, $i, 1 );
     $i = $i + 1; //实际的Byte数仍计1个
     $n ++; //但考虑整体美观，大写字母计成一个高位字符
    }elseif ($ascnum >= 97 && $ascnum <= 122) {
      $returnstr = $returnstr . substr ( $sourcestr, $i, 1 );
      $i = $i + 1; //实际的Byte数仍计1个
      $n ++; //但考虑整体美观，大写字母计成一个高位字符
    } else {//其他情况下，半角标点符号，
     $returnstr = $returnstr . substr ( $sourcestr, $i, 1 );
     $i = $i + 1; 
     $n = $n + 0.5; 
    }
   }
   return $returnstr;
}

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