Call a function before main [duplicate]

Answer 1

In C++ there is a simple method: use the constructor of a global object.

class StartUp
{
public:
   StartUp()
   { foo(); }
};

StartUp startup; // A global instance

int main()
{
    ...
}

This because the global object is constructed before main() starts. As Lundin pointed out, pay attention to the static initialization order fiasco.