Intro

#include <iostream>
using namespace std;

int main(){

/*
//int* p,q,r; //q and r are not pointers
int* p;
int* q;
int* r;
int *p, *q, *r; //p, q and r are all pointers
*/

int a;
int *iptr;

a = 2;
iptr = &a;

cout<<a<<endl; //2
cout<<iptr<<endl; //address of iptr

*iptr = 6;
cout<<a<<endl; //6

return 0;
}

#include <iostream>

using namespace std;

//passing by reference using pointers

void swap(int& x, int& y){
    int temp = x;
    x = y;
    y = temp;
}

void swap_p(int* xp, int* yp){
    int temp = *xp;
    *xp = *yp;
    *yp = temp;
}

int main(){
    int a=3, b=4;
    cout<<a<<" "<<b<<endl; //3 4

    swap(a, b);
    cout<<a<<" "<<b<<endl; //4 3 

    swap_p(&a, &b);
    cout<<a<<" "<<b<<endl; //3 4
    return 0;
}