Embedded Programming with Modern C++/

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nullptr Instead of 0 or NULL

nullptr Instead of 0 or NULL

In this lesson, we will learn how new null pointer nullptr cleans up in C++ with the ambiguity of the number 0 and the macro NULL.

We'll cover the following...

The Number 0

The issue with the literal 0 is that it can be either the null pointer (void*)0 or the number 0 depending on the context of the problem in question.

Therefore, programs using the number 0 should be confusing.

C++
// null.cpp
#include <iostream>
#include <typeinfo>
int main(){
  std::cout << std::endl;
  int a = 0;
  int* b = 0;
  auto c = 0;
  std::cout << typeid(c).name() << std::endl;
  auto res = a + b + c;
  std::cout << "res: " << res << std::endl;
  std::cout << typeid(res).name() << std::endl;
  
  std::cout << std::endl;
}

The question remains, what is the data type of variable c in line 12 and of variable res in line 15?

The variable c is of type int and the variable res is of type pointer to int: int*. Pretty simple, right? The expression a + b + c in line 15 is pointer arithmetic.

The macro NULL

The issue with the null pointer NULL is that it implicitly converts to int.

According to ...