So I'm studying for my final and I'm trying to understand what are some of the tradeoffs between creating a class function or a global function (consider operator functions I suppose, my professor mentioned that some operator functions MUST be global, and I didn't really understand). If anyone could help me understand this I would be grateful, thanks!

Suppose you're writing classes to represent vectors as defined mathematicians. (Note: *not* the ugly things in the C++ standard library.)

 

For example, the product of a vector and a scalar is a vector. That's easy: Just overload operator* in your Vector class. However, the product of a scalar and a vector also is a vector. Now you've got a problem. The argument to operator* as a member function is a multiplier, not a multiplicand. You have but no choice but to make this overload a friend function rather than a member function.

I am trying to understand how global variables and functions work in C.

 

void do_work()

{

int bar = foo();

}