Can #if pre-processor directives be nested in C++?

Question

I have a question about Pre-processor directives in c++:

For example:

#ifndef QUESTION

//some code here

#ifndef QUESTION

//some code here

#endif
         


        

Answer 1

Yes, we can. The #endif statement matches to the previous #if #ifdef or #ifndef etc for which there hasn't been a corresponding #endif.

e.g.

#if  ----------|
#if  -----|    |
#endif ---|    |
#endif --------|