References in C++
This post and the examples are from the Microsoft C++ Documentation.
A reference is an alias of another object. It stores the address of an object that is located elsewhere in memory. Unlike a pointer, a reference cannot be set to NULL when initializing, and cannot be reassigned to refer to a different object after initialization.
There are two kinds of references: lvalue references which refer to a named variable, and rvalue references which refer to a temporary object. The & operator signifies an lvalue reference and the operator signifies either an rvalue reference, or a universal reference (either rvalue or lvalue depending on the context).
Below is an example of using references.
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#include <stdio.h>
struct S {
short i;
};
int main() {
S s; // Declare the object.
S& SRef = s; // Declare the reference.
s.i = 3;
printf_s("%d\n", s.i);
printf_s("%d\n", SRef.i);
SRef.i = 4;
printf_s("%d\n", s.i);
printf_s("%d\n", SRef.i);
}
The output of the above coe is:
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When changing the i value of either s or SRef, the other one changes too. This is because both SRef and s are pointing to the same object.