When to Use Pointers over References

While references are generally preferred in modern C++, there are still situations where pointers are necessary or more appropriate:

1. When you need to represent the absence of a value. A pointer can be null, while a reference must always refer to an object.
2. When you need to change what a pointer points to. References cannot be reassigned after initialization.
3. When you need to do arithmetic on the address. Pointer arithmetic is not possible with references.
4. When interfacing with legacy code that uses pointers.

Here's an example where a pointer is used to represent the absence of a value:

1#include <iostream>
2
3void Print(const int* ptr) {
4  if (ptr) {
5    std::cout << "Value: " << *ptr << "\n";
6  } else {
7    std::cout << "Null pointer\n";
8  }
9}
10
11int main() {
12  int x = 10;
13  int* ptr1 = &x;
14  int* ptr2 = nullptr;
15
16  Print(ptr1);
17  Print(ptr2);
18}

1Value: 10
2Null pointer