//截取想這樣的字符串a李三

/** *  * 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 ( $sourcestr ); //字符串的字節數    while ( ($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碼     if ($ascnum >= 224) {//如果ASCII位高與224，       $returnstr = $returnstr . substr ( $sourcestr, $i, 3 ); //根據UTF-8編碼規范，將3個連續的字符計為單個字符         $i = $i + 3; //實際Byte計為3       $n ++; //字串長度計1    } elseif ($ascnum >= 192){ //如果ASCII位高與192，       $returnstr = $returnstr . substr ( $sourcestr, $i, 2 ); //根據UTF-8編碼規范，將2個連續的字符計為單個字符        $i = $i + 2; //實際Byte計為2       $n ++; //字串長度計1    } elseif ($ascnum >= 65 && $ascnum <= 90) {//如果是大寫字母，     $returnstr = $returnstr . substr ( $sourcestr, $i, 1 );     $i = $i + 1; //實際的Byte數仍計1個     $n ++; //但考慮整體美觀，大寫字母計成一個高位字符    }elseif ($ascnum >= 97 && $ascnum <= 122) {      $returnstr = $returnstr . substr ( $sourcestr, $i, 1 );      $i = $i + 1; //實際的Byte數仍計1個      $n ++; //但考慮整體美觀，大寫字母計成一個高位字符    } else {//其他情況下，半角標點符號，     $returnstr = $returnstr . substr ( $sourcestr, $i, 1 );     $i = $i + 1;      $n = $n + 0.5;     }   }   return $returnstr;}