search multiple words in text file

Hello,

I have data in a text file that I want users to be able to search. I can have them search for one word, but I need to make it so they can search for several words. I've looked all over for tutorials on something like this, but haven't found anything... here is basically how I'm searching for one word:

if ($word==NULL) { $word="00";

if ((strpos($file,$word)>=1)) {

loop thru displaying results, increasing counter with each loop until all results displayed


any suggestions or links to tutorials on how to do this with more than one word would be greatly appreciated.