its impossible to view the php code from the browser. the reason is because the code is run and based on the code, it generates output, and showing the actual code is unnecessary and also is a privacy issue. sites like google, yahoo or ebay wouldnt like it if someone could just view source and see how their multi million dollar programs work!
also, php is a server side scripting language, meaning the code is interpreted and handled by the server, where javascript (which you can view the full source of in the browser) is client side, meaning the user's browser processes the code. a user can disable javascript because its handled by the browser, but could not disable php because its handled by the remote server.