Call a C++ function from Swift - c++

Question

How should I call a C++ function (no classes involved) from a Swift file?
I tried this:
In someCFunction.c:
void someCFunction() {
printf("Inside the C function\n");
}
void aWrapper() {
someCplusplusFunction();
}
In someCpluplusfunction.cpp:
void someCplusplusFunction() {
printf("Inside the C++ function");
}
In main.swift:
someCFunction();
aWrapper();
In Bridging-Header.h:
#import "someCFunction.h"
#import "someCplusplusFunction.h"
I found this answer very informative, but still I cannot make it work.
Could you point me in the right direction?
Thanks!

Answer 1

What does the header look like?
If you want to explicitly set the linking type for C-compatible functions in C++, you need to tell the C++ compiler so:
// cHeader.h
extern "C" {
void someCplusplusFunction();
void someCFunction();
void aWrapper();
}
Note that this isn't valid C code, so you'd need to wrap the extern "C" declarations in preprocessor macros.
On OS X and iOS, you can use __BEGIN_DECLS and __END_DECLS around code you want linked as C code when compiling C++ sources, and you don't need to worry about using other preprocessor trickery for it to be valid C code.
As such, it would look like:
// cHeader.h
__BEGIN_DECLS
void someCplusplusFunction();
void someCFunction();
void aWrapper();
__END_DECLS
EDIT: As ephemer mentioned, you can use the following preprocessor macros:
// cHeader.h
#ifdef __cplusplus
extern "C" {
#endif
void someCplusplusFunction();
void someCFunction();
void aWrapper();
#ifdef __cplusplus
}
#endif