writing source code to file

I was wondering if there was a block of code I could place at the bottom of the file that would write the page's source code to an html file. I need this because I'm posting pages to a server sans a PHP compiler. Basically, I'd like for every time I run a page its source code to be saved in the filename of my choice, instead of me having to run the page, copy the source, and paste it into the file of my choice. I know how to use fopen, but I'm not sure what to tell it to write to file, since the source I want to write is being generated simultaneously. Any help would be greatly appreciated...