C++ Programming
C++ Support
The WM IoT SDK is primarily written in C and provides C language APIs, but it also supports the development of applications using C++.
The highest version of C++ supported by the WM IoT SDK is GNU++14 (or C++14). However, due to the resource constraints of embedded devices, not all C++ features are supported, such as:
Exception handling mechanismiostream
Mixed C/C++ Programming
The WM IoT SDK supports mixed C/C++ programming, meaning that code written in C can call code written in C++, and vice versa.
When different parts of an application are developed using C and C++, special attention must be paid to the calling rules for mixed C/C++ programming.
Calling C++ Code from C
To be able 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 be able 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()
{
// ...
}