The first example won't compile with any compliant compiler. If you find it compining in VC++, then you have a very old VC++ or you have errors and warnings disabled.
Aside from that, notice that you have no code in "main". "Main" is the entry and exit point for your program. Nothing going on there.
The return value of "printf" is the number of characters printed, or a negative number if an error occurs. I'm not sure what you're planning to do with that. The integer obviously can't be assigned to until the function is run, so you need a valid invocation, not a global kind of declaration.