PHP는 이미지 코드를 무작위로 표시합니다.

php通过rand()函数产生随机数，这个函数可以产生一个指定范围的数字
这段代码通过产生的随机数，随机选择图片

  srand( microtime() * 1000000 );
  $num = rand( 1, 4 );

  switch( $num )
  {
  case 1: $image_file = "/home/images/alfa.jpg";
          break;
  case 2: $image_file = "/home/images/ferrari.jpg";
          break;
  case 3: $image_file = "/home/images/jaguar.jpg";
          break;
  case 4: $image_file = "/home/images/porsche.jpg";
          break;
  }
  echo "Random Image : ";
?>

PHP