How Can I Call C Functions from C Code and Avoid Name Mangling Issues?

Calling C Functions from C: Navigating Name Mangling

When working with mixed-language applications, the challenge of calling C functions from within C arises due to C 's name mangling. Unlike C, which uses simple function names, C employs a complex naming scheme to resolve overloaded functions and classes, resulting in different function signatures. This can lead to linker errors when attempting to resolve unresolved symbols.

In such cases, a workaround involves creating a C API that provides access to the C functionality. This entails writing C code declared as extern "C" and adhering to a pure C syntax, avoiding object-oriented features like classes. Subsequently, a C wrapper library is created to expose the functionality of the C library.

For example, consider the following C API:

#ifdef __cplusplus
#define EXTERNC extern "C"
#else
#define EXTERNC
#endif

typedef void* mylibrary_mytype_t;

EXTERNC mylibrary_mytype_t mylibrary_mytype_init();
EXTERNC void mylibrary_mytype_destroy(mylibrary_mytype_t mytype);
EXTERNC void mylibrary_mytype_doit(mylibrary_mytype_t self, int param);

#undef EXTERNC

The corresponding C implementation would be as follows:

mylibrary_mytype_t mylibrary_mytype_init() {
  return new MyType;
}

void mylibrary_mytype_destroy(mylibrary_mytype_t untyped_ptr) {
   MyType* typed_ptr = static_cast<MyType*>(untyped_ptr);
   delete typed_ptr;
}

void mylibrary_mytype_doit(mylibrary_mytype_t untyped_self, int param) {
   MyType* typed_self = static_cast<MyType*>(untyped_self);
   typed_self->doIt(param);
}

This approach allows you to access C functionality from C code while mitigating name mangling issues.

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