Are there benefits of passing by pointer over passing by reference in C++?

A pointer can receive a null parameter whereas a reference can’t. You can only use pointer if you want to pass “no object”.

Explicitly passing by pointer allow us to see the whether the object is passes by reference or value at call site.

These are simple example of passing by pointer and passing by reference −

Passing by pointer

Example

#include <iostream>
using namespace std;
void swap(int* a, int* b) {
   int c = *a;
   *a= *b;
   *b = c;
}
int main() {
   int m =7 , n = 6;
   cout << "Before Swap\n";
   cout << "m = " << m << " n = " << n << "\n";
   swap(&m, &n);
   cout << "After Swap by pass by pointer\n";
   cout << "m = " << m << " n = " << n << "\n";
}

Output

Before Swap
m = 7 n = 6
After Swap by pass by pointer
m = 6 n = 7

Passing by reference

Example

#include <iostream>
using namespace std;
void swap(int& a, int& b) {
   int c = a;
   a= b;
   b = c;
}
int main() {
   int m =7 , n = 6;
   cout << "Before Swap\n";
   cout << "m = " << m << " n = " << n << "\n";
   swap(m, n);
   cout << "After Swap by pass by reference\n";
   cout << "m = " << m << " n = " << n << "\n";
}

Output

Before Swap
m = 7 n = 6
After Swap by pass by reference
m = 6 n = 7