Question

I’ve been programming with SDL for a while, and I decide to make a header file to simplify my coding. Now I have a question; if I pass a function parameter I don’t want, should I do

test(NULL);

from the Windows API I include or

test(false);

I use C++, NOT C.

Answer 1

It completely depends on what the function parameter type is. If it’s a pointer, and the documentation says that it’s valid, then you can pass the C++ NULL (which is just 0 in reality).

Examples:

// Bad; strlen expects a pointer to a real, existing C-string buffer
std::cout << strlen(NULL);

/**
 * Function that does something.
 * 
 * @param ptr Pointer to buffer, or NULL to do nothing
 */
void myFunc(const char* ptr);

// OK; the function is designed to be ok with it
myFunc(NULL);

So not all functions will accept this as valid for a pointer.

It certainly won’t be valid for any other type (though you’ll get away with passing it for an int, it’s not quite what you’d expect to do). NULL is not a catch-all “I want to opt out of this function parameter”. You simply can’t do that in the general case.

Conclusion: It depends what test is.

And I have no idea what null is supposed to be.