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C++ Programming

C++ Support

The WM IoT SDK is primarily written in C and provides C language APIs, but it also supports application development in C++.

• Exception handling mechanism

• iostream

C/C++ Mixed Programming

The WM IoT SDK supports mixed C/C++ programming, meaning code written in C can call code written in C++, and vice versa.

When different parts of an application are developed in C and C++, special attention must be paid to the calling rules of mixed C/C++ programming.

Calling C++ Code from C

To call a C++ function from C code, the C++ function must be declared and defined with C linkage using extern "C":

// Declaration in .h file:
#ifdef __cplusplus
extern "C" {
#endif

void my_cpp_func(void);

#ifdef __cplusplus
}
#endif

// Definition in .cpp file:
extern "C" void my_cpp_func(void)
{
    // ...
}

Calling C Code from C++

To call a C function from C++, the C function must be declared with C linkage:

// Declaration in .h file:
#ifdef __cplusplus
extern "C" {
#endif

void my_c_func(void);

#ifdef __cplusplus
}
#endif

// Definition in .c file:
void my_c_func(void)
{
    // ...
}

Defining main in C++

The WM IoT SDK expects the application entry point main to be defined with C linkage. When main is defined in a .cpp source file, it must be marked with extern "C":

extern "C" void main()
{
    // ...
}