Method of Intercepting Chinese English Mixed Strings by php

php interception should be a string, so there is no need to use substr or mb_substr

// Intercept a string like this 
a Li 3

Using ASCII

/**
 * 
 *  Chinese-English mixed string interception 
 * @param unknown_type $sourcestr
 * @param unknown_type $cutlength
 */
function assoc_substr($sourcestr, $cutlength) {
   $returnstr = '';
   $i = 0;
   $n = 0;
   $str_length = strlen ( $sourcestr ); // Number of bytes of string  
   while ( ($n < $cutlength) and ($i <= $str_length) ) {
    $temp_str = substr ( $sourcestr, $i, 1 );
    $ascnum = Ord ( $temp_str ); // Get the first in the string $i Bit character ascii Code  
    if ($ascnum >= 224) {// If ASCII Position height and 224 , 
       $returnstr = $returnstr . substr ( $sourcestr, $i, 3 ); // According to UTF-8 Coding specification, which will 3 Consecutive characters are counted as a single character   
       $i = $i + 3; // Actual Byte Count as 3
       $n ++; // String length meter 1
    } elseif ($ascnum >= 192){ // If ASCII Position height and 192 , 
       $returnstr = $returnstr . substr ( $sourcestr, $i, 2 ); // According to UTF-8 Coding specification, which will 2 Consecutive characters are counted as a single character  
       $i = $i + 2; // Actual Byte Count as 2
       $n ++; // String length meter 1
    } elseif ($ascnum >= 65 && $ascnum <= 90) {// If it's a capital letter, 
     $returnstr = $returnstr . substr ( $sourcestr, $i, 1 );
     $i = $i + 1; // Actual Byte Counting 1 A 
     $n ++; // However, considering the overall beauty, the capital letters are calculated 1 High-order characters 
    }elseif ($ascnum >= 97 && $ascnum <= 122) {
      $returnstr = $returnstr . substr ( $sourcestr, $i, 1 );
      $i = $i + 1; // Actual Byte Counting 1 A 
      $n ++; // However, considering the overall beauty, the capital letters are calculated 1 High-order characters 
    } else {// In other cases, half-angle punctuation marks, 
     $returnstr = $returnstr . substr ( $sourcestr, $i, 1 );
     $i = $i + 1; 
     $n = $n + 0.5; 
    }
   }
   return $returnstr;
}

Summarize