References
Reference
Reference is an alternative name for an object. In the code below, r becomes another name of 'a'.
int a = 5;
int &r = a;
Here, r can be considered as a macro for (*p), where p is a pointer to 'a'.
Demo Code
#include <iostream>
using namespace std;
void swap1(int i, int j) // cannot swap because i and j are local copies inside this function
{
int tmp = i;
i = j;
j = tmp;
}
void swap2(int *ip, int *jp) // can swap because ip and jp are pointers, pointing to the outside integers
{
int tmp = *ip;
*ip = *jp;
*jp = tmp;
}
void swap3(int& i, int& j) // can swap because i and j are references, they are alternative names of the outside integers
{
int tmp = i;
i = j;
j = tmp;
}
int main()
{
int x = 10;
int y = 20;
swap1(x,y);
cout << x << ", " << y << endl;
swap2(&x,&y);
cout << x << ", " << y << endl;
swap3(x,y);
cout << x << ", " << y << endl;
}