On http://php.net/strstr you can see the following note:

> If you only want to determine if a particular needle occurs within haystack, use the faster and less memory intensive function strpos() instead.

I think that this is what you try to achieve here.

It is generally not correct to test result of `strstr()`/`strpos()` without using `!== false` as those functions could return `0` if the needle is found at the beginning of the string and `0` evaluates to `false`.