How to call a C++ method from C? [duplicate]

Answer 1

You cannot invoke a C++ method directly in C. Instead you may create a C wrapper and then call that:

C/C++ compatible header file:

#ifdef __cplusplus
extern "C" {
#endif

struct MyClass;

MyClass *new_MyClass();

void MyClass_sendCommandToSerialDevice(MyClass *c, int Command, int Parameters, int DeviceID);

#ifdef __cplusplus
} // extern "C"
#endif

implementation (a .cpp file)

#include "my_c_compatiblity_header.h"
#include "MyClass.h"

extern "C" MyClass *new_MyClass() { return new MyClass(); }

extern "C"
void MyClass_sendCommandToSerialDevice(MyClass *c, int Command, int Parameters, int DeviceID) {
    c->sendCommandToSerialDevice(Command, Parameters, DeviceID);
}

main.c

int main(int argc, char ** argv) {
    MyClass *c = new_MyClass();
    MyClass_sendCommandToSerialDevice(c, 1, 0, 123);
}

Of course since resource and error handling can be different between C and C++ code you'll have to work out how to handle the combination in your case. For example the above just leaks a MyClass object instead of cleaning up, and doesn't do anything about exceptions.