macros - How to trigger the __cplusplus (C++) #ifdef? -

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#ifdef __cplusplus // c++ code #else // c code #endif

the structure this. question is, how trigger #ifdef on?

i mean, in program? code write can turn #ifdef on?

for example, in case. 

#define __cplusplus

will turn on?

"#define __cplusplus"

will let on?

yes, "let on".

__cplusplus should automatically defined c++ compiler. c++ uses different name mangling , macro used make c headers compatible c++:

#ifdef __cplusplus extern "c" { #endif  ...  #ifdef __cplusplus } #endif

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