C++ nullptr

C++ nullptr – The Modern Way to Say “No Address”

In C++, if a pointer doesn’t point anywhere, we say it’s null. Before C++11, we used NULL. But now we have something better — nullptr!

nullptr is a special keyword that means “this pointer points to nothing.”

Why use nullptr?

• Type-safe – It’s only for pointers
• Modern – Recommended since C++11
• Prevents bugs – No accidental confusion with integers

Example: Using nullptr with Pointers

#include <iostream>
using namespace std;

void greet(int* p) {
    if (p == nullptr) {
        cout << "Pointer is null!" << endl;
    } else {
        cout << "Value: " << *p << endl;
    }
}

int main() {
    int* ptr = nullptr;
    greet(ptr);  // Will say "Pointer is null!"

    int x = 42;
    ptr = &x;
    greet(ptr);  // Will print the value

    return 0;
}
  

nullptr vs NULL vs 0

• NULL – Old C-style (actually just 0)
• 0 – Dangerous, could be confused with int
• nullptr – Modern and safe (best choice)

Summary

• nullptr represents a null (empty) pointer
• Use it to avoid bugs and write modern C++
• Always prefer nullptr over NULL or 0

So next time you want to say “this pointer goes nowhere,” say it like a pro — use nullptr!