@SyCoApr 29.2008 — #There was a time a few years ago when people called their includes include.inc but .inc files are treated as text files by the server so you could access the source. Any page with a .php extension is safe from viewing unless you get your code horribly wrong! ?
show_source() wont give external access to you php code, it's simply an alias of highlight_file().
@felgallApr 29.2008 — #If you do use .inc for the file type then you can always associate that with PHP from within the .htaccess file and also add a single command into the top of the file that blocks it being accessed separately.