30. Select Driver Overload

#include <iostream>
using namespace std;

void init(int pin) {
    cout << "PIN " << pin;
}

void init(int* portPtr) {
    cout << "PORT NULL";
}

int main() {
    int mode;
    cin >> mode;

    if (mode == 1) {
        int pin;
        cin >> pin;
        init(pin);        // calls int overload
    }
    else if (mode == 2) {
        init(nullptr);    // calls pointer overload
    }

    return 0;
}

Explanation & Logic Summary:

• Two overloads exist: one takes int, one takes int*
• Using 0 or NULL can select the wrong overload
• nullptr enforces pointer overload selection
• Output confirms which overload was executed

Firmware Relevance & Real-World Context:

• HAL APIs often overload based on:
  • pin vs port
  • index vs pointer
  • buffer vs size
• Passing 0 can silently:
  • select pin 0 unintentionally
  • bypass pointer-based initialization
• nullptr eliminates these ambiguity-driven bugs