Pointer vs Reference Swap

#include <iostream>

void swapPtr(int* a, int* b){
    if(a != nullptr || b != nullptr){
        int temp = *a;
        *a = *b;
        *b = temp;
    }
}


void swapRef(int& a, int& b){
    int temp = a;
    a = b;
    b = temp;
}

int main() {
    int x, y;
    std::cin >> x >> y;

    int a = x, b = y;
    swapPtr(&a, &b);
    std::cout << "After swapPtr: a=" << a << " b=" << b << "\n";

    int c = x, d = y;
    swapRef(c, d);
    std::cout << "After swapRef: a=" << c << " b=" << d;

    return 0;
}

Solving Approach