In C++, what does & mean after a function's return type?

Question

In a C++ function like this:

int& getNumber();

what does the & mean? Is it different from:

int getNumb         


        

Answer 1

int& getNumber(): function returns an integer by reference.

int getNumber(): function returns an integer by value.

They differ in some ways and one of the interesting differences being that the 1st type can be used on the left side of assignment which is not possible with the 2nd type.

Example:

int global = 1;

int& getNumber() {
        return global; // return global by reference.
}

int main() {

        cout<<"before "<

Ouptput:

before 1
after 2