title: Disable language extensions, #ifndef fails
body: <p>This question refers to Visual Studio C++ 2010. If I disable language extensions, even the simplest toy program gets an error of "unexpected end-of-file found" when I include even an empty .h file. It appears that the problem lies with the #ifndef HEADER_THING trick for not including a header twice. If I omit that, the error message goes away.</p>