How does extern “C” work in C++? [duplicate]

StackOverflow https://stackoverflow.com/questions/9190493

  •  27-04-2021
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Question

I see some code in C++ using extern "C" at the beginning of the file like this:

#ifdef __cplusplus 
extern "C" {} 
#endif

What does this mean? How does it work?

Was it helpful?

Solution

It's probably not like that, but more like:

#ifdef __cplusplus 
extern "C" {
#endif

//some includes or declarations

#ifdef __cplusplus 
}
#endif

It tells the compiler to use C name mangling for whatever is declared inside the directives.

The way you have it now:

#ifdef __cplusplus 
extern "C" {} 
#endif

is just dead code.

OTHER TIPS

It is used to inform the compiler to disable C++ name mangling for the functions defined within the braces. http://en.wikipedia.org/wiki/Name_mangling

Extern "C" - notify the compiler,that the noted function is compiled in C style.

It specifies a linkage specification.
It tells the linker how to link the code.

It is useful when you want to mix C and C++ code.

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