A function declaration is statement of what a function's signature looks like. A function's signature is a combination of the function's name; the number, order, and types of its parameters; as well as any qualifiers that can be applied to the function. Sometimes function signatures are called "method signatures" because they belong to the member function of a class. A method is identical in all respects to a "normal" function except that a method always belongs to an object or class.

Every function in the same program must have a unique signature so the compiler knows which one is being called at any point in the code. When there are two or more functions in the same program that have the same name but have different signatures, the function is said to be overloaded. Because the function signatures are different, it therefore follows that the function...