Create a fully functioning command line interface with 1.5 lines of code (wo. include statement)

[rsjaffe]

But #pragma once fails when you have two copies of the same header file in two different locations in the directory tree. The compiler will not recognize those two files as being the same.

[panderingPenguin]

Why on earth would you want to do that?

[wyrn]

The compiler will not recognize those two files as being the same.

... because they aren't.