Question

I have a class and I want that when I give it as a parameter for printf/sprintf that it is being used as a specific string (depending on whats going on in the class). Is something like that possible ?

printf("blah blah  %s  ", customclass);

What do I have to do that this happens without any kind of typecasting and without any kind of necessary function call like customclass.xyz() ?

Answer 1

printf is a variadic function, which cannot be used in any sensible manner with user-defined types.

If you’re in C++, you should prefer streams (e.g. std::cout) to printf for exactly this sort of reason. With streams, you can overload the << operator:

class CustomClass
{
public:
    int x;
    int y;
};

ostream &operator<<(ostream &os, CustomClass c)
{
    os << "{" << c.x << "," << c.y << "}";
    return os;
}

...

CustomClass customclass;
customclass.x = 5;
customclass.y = 7;
std::cout << customclass << "\n";