29. Overload Resolution Trap

#include <iostream>
using namespace std;

void foo(int x) {
    cout << "int overload\n";
}

void foo(int* p) {
    cout << "int* overload\n";
}

int main() {
    foo(0);
    foo(nullptr);
    return 0;
}

Explanation & Logic Summary:

• 0 is an integer literal, so overload resolution selects foo(int).
• nullptr has type std::nullptr_t and converts only to pointer types, so foo(int*) is selected.
• This behavior is guaranteed by the C++ standard, unlike NULL.

Firmware Relevance & Real-World Context:

• Firmware APIs often overload functions for:
  • Scalar configuration values
  • Pointer-based buffers or structures
• Using nullptr instead of integer literals or macros prevents:
  • Accidental selection of the wrong overload
  • Subtle runtime bugs caused by incorrect API paths
• This practice improves type safety, readability, and portability in embedded C++ code.