What else can we write with ‘#’ apart from ‘include’?

Answer 1

#define and #pragma

Answer 2

#ifdef #endif #else etc.

Answer 3

#undef, #warning, #error, #line too

Answer 4

http://www.cplusplus.com/doc/tutorial/preprocessor/

Answer 5

#region /#endregion for code collapsing

Answer 6

called preprocessor directives