Please can any one tell me where to edit the code such that - when user search members -- they get only opposite sex members in search result, means male memebrs only and always get  female profile in user search result and vice versa

I know that we have to get gender of current logged-in user and then based on that we have to filter member search result for getting opposite gender profiles only, but I don't know where to edit in core oxwall files

please help me in doing so

Thanks

Dhananjay