A word in a string

[b_hole]

I'm trying to check if a specific word exists in a specific string. For that I'm using strpos function, like this:
if (strpos($str, $word)==0) // do something

But this statement returns true also when $word is the first word in $str. How can I workaround this problem?

Thanks.

[dumpfi]

if(FALSE === strpos($str, $word))
{
// $word is not in $str
}dumpfi

[b_hole]

Thanks :)