You can't. It's built into compilers to allow you overloading functions and to have functions with the same name in different classes and such stuff. But you can write functions that are mangled like C functions. Those can be called from C code. But those can't be overloaded and can't be called by "normal" C++ function pointers:
extern "C" void foo() {
}
The above function will be mangled like C functions for your compiler. That may include no change at all to the name, or some changes like a leading "_" in front of it or so.
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