References

int* ptr = &var;

ptr holds the address to var

int x = 99;
int &y = x;

y++;

// x and y are now 100

Dereference

int var1 = *ptr;

var1 now holds the value of ptr not the address

nullptr alternative

#include <stdio.h>

int * ptr = NULL;

Pass by reference

int a = 1000;
int b = 2000;

void func(int &i, int &j){
	i = 10;
	j = 20;
}

func(a, b);

In the example above the actual values of a and b will be changed to 10 and 20 respectively.

This can be more efficient, especially with const values.