PHP is SERVER SIDE, i.e. IT ONLY GENERATES TEXT / IMAGES, and NO-ONE besides Apache ever really sees any of your PHP code.
Thus, the Search Engine will see EXACTLY what your browser sees, and EXACTLY what you see when you choose ' View => Source '
People need to remember that PHP is Server-side only, your actual PHP code never gets sent to a browser / search engine / wget / Curl, it gets parsed before this and whatever HTML / XML / Image you told it to output is what gets seen.
This is why you can't do things like get teh screen resolution of the user, or upload a file without submitted a page, etc.
Remember that PHP is Server-Side, Javascript / Flash are Client-Side.