nullptr pointer literal

 

C++

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Syntax

nullptr		(since C++11)

Explanation

The keyword nullptr denotes the null pointer literal. It is an unspecified prvalue of type std::nullptr_t. There exist implicit conversions from nullptr to null pointer value of any pointer type and any pointer to member type. Similar conversions exist for any value of type std::nullptr_t as well as for the macro NULL, the null pointer constant.

Example

Demonstrates how nullptr allows forwarding via a template function.

run this code

#include <cstddef>
#include <iostream>
 
template<class F, class A>
void Fwd(F f, A a)
{
    f(a);
}
 
void g(int* i)
{
    std::cout << "Function g called\n";
}
 
int main()
{
    g(NULL);           // Fine
    g(0);              // Fine
 
    Fwd(g, nullptr);   // Fine
//  Fwd(g, NULL);  // ERROR: No function g(int)
}

Output:

Function g called
Function g called
Function g called

Keywords

nullptr

See also

NULL	implementation-defined null pointer constant (macro constant)
nullptr_t (C++11)	the type of the null pointer literal nullptr (typedef)