php读取txt是乱码怎么办

  //$fname文件名称
   if ($fname = $_FILES['nickname']['tmp_name']) {
 
          //file_get_contents() 函数把整个文件读入一个字符串中。
          $contents = file_get_contents($fname);
             //获取文件的编码方式
          $encoding = mb_detect_encoding($contents, array('GB2312','GBK','UTF-16','UCS-2','UTF-8','BIG5','ASCII'));
 
          $fp=fopen($fname,"r");//以只读的方式打开文件
          $text = "";
          $num = 0;
          if(!(feof($fp))) {
              $num++;
              $str = trim(fgets($fp));
              if ($encoding != false) {
          //iconv ()将$encoding 转换成“UTF-8”
                  $str = iconv($encoding, 'UTF-8', $str);
                  if ($str != "" and $str != NULL) {
                      $text = $str;
                  }
              }
              else {
                  $str = mb_convert_encoding ( $str, 'UTF-8','Unicode');
                  if ($str != "" and $str != NULL) {
                      $text = $str;
                  }
              }
          }
          while(!(feof($fp))) {
              $str = '';
              $str = trim(fgets($fp));
              if ($encoding != false) {
                  $str = iconv($encoding, 'UTF-8', $str);
                  if ($str != "" and $str != NULL) {
                      $text = $text.",".$str;
                  }
              }
              else {
                  $str = mb_convert_encoding ( $str, 'UTF-8','Unicode');
                  if ($str != "" and $str != NULL) {
                      $text = $text.",".$str;
                  }
              }
          }
      }