What is an arrow operator, -> in C++?

C++Server Side ProgrammingProgramming

The dot and arrow operator are both used in C++ to access the members of a class or structure. They are just used in different scenarios. In C++, types declared as class, struct, or union are considered "of class type". So the following refers to all three of them.

• a.b is only used if b is a member of the object (or reference to an object) a. So for a.b, a will always be an actual object (or a reference to an object) of a class.

• a->b is essentially a shorthand notation for (*a).b, i.e., if a is a pointer to an object, then a->b is accessing the property b of the object that a points to.

Note that dot cannot be overloaded but -> can be overloaded, so we can define our own function(operator->()) that should be called when this operator is used. so if a is an object of a class that overloads operator-> (common such types are smart pointers and iterators), then the meaning is whatever the class designer implemented.

References are, semantically, aliases to objects, so I should have added "or reference to a pointer" to the as well. However, I thought this would be more confusing than helpful, since references to pointers (T*&) are rarely ever used.

Example Code

#include<iostream>
class A {
public: int b;
A() { b = 5; }
};
int main() {
A a = A();
A* x = &a;
std::cout << "a.b = " << a.b << "\n";
std::cout << "x->b = " << x->b << "\n";
return 0;
}

Output

5
5
Published on 14-Mar-2019 11:10:29