检测嗡嗡声的机器人？ [重复]

I need an if statement that will include a file on my page only if it detects crawlers from google, bing and yahoo. I found this code on another post but I want to add bing and yahoo too:

if(strstr(strtolower($_SERVER['HTTP_USER_AGENT']), "googlebot"))
{
    //MY CODE
}

I would really appreciate if someone could solve this problem for me.

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Crawler user-agents can be found here. Filtering out the ones you want should be trivial. On a sidenote, don't use strstr() for these kind of checks, strpos() is faster and less memory intensive. And you should typecheck against FALSE, because either function may return a value that evaluates to false.

$ua = strtolower($_SERVER['HTTP_USER_AGENT']);
if (strpos($ua, "googlebot") !== false || strpos($ua, "bingbot") !== false || … ) {
    // do something
}