Lesson 114 +10 XP

Create References

A reference is another name for an existing variable - an alias. Two names, one object, no copy.

Declaring a reference

#include <string>
using namespace std;

string food = "Pizza";
string &meal = food;   // meal is a reference to food

food is a normal string.
meal is a reference to food - a second name for the same data.

The & that appears in the declaration (right after the type) is what makes meal a reference.

Two names, one value

cout << meal << endl;   // Pizza
cout << food << endl;   // Pizza

Both names print the same value, because both refer to the same location. Change one name and the change is visible through the other:

meal = "Burger";
cout << food << endl;   // Burger

Same memory address

A reference makes no copy - meal and food are literally the same object. They even share the same memory address:

cout << &food << endl;   // 0x7ffe0000a1c
cout << &meal << endl;   // 0x7ffe0000a1c  (same!)

Where the & goes

The & in string &meal is part of the declaration - it signals "this name is a reference". A reference must be bound to a variable when it is declared; there is no "empty reference".

TL;DR

A reference is an alias: another name for an existing variable.
Declare it with & after the type: string &meal = food;.
No copy - both names share the same memory address.
Changing one name changes the other, because they are one object.

Create References