<?
srand((double)microtime()*1000000);
$randval = rand(0,5);
switch($randval)
{
case "0";
echo "广告代码1";
break;
case "1";
echo "广告代码2";
break;
case "2";
echo "广告代码3";
break;
case "3";
echo "广告代码4";
break;
case "4";
echo "广告代码5";
break;
}
?>