Varianti

    std::nullptr_t

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    <tbody> </tbody>
    Elemento definito nell'header <cstddef>
    typedef decltype(nullptr) nullptr_t;
    		 (dal C++11)
    std::nullptr_t è il tipo di puntatore nullo letterale, nullptr.
    Original:
    std::nullptr_t is the type of the null pointer literal, nullptr.
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    Esempio

    Se due o più sovraccarichi accettare diversi tipi di puntatore, un sovraccarico per std::nullptr_t è necessario accettare un argomento puntatore nullo .
    Original:
    If two or more overloads accept different pointer types, an overload for std::nullptr_t is necessary to accept a null pointer argument.
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    #include <cstddef>
#include <iostream>

void f(int* pi)
{
   std::cout << "Pointer to integer overload\n";
}

void f(double* pd)
{
   std::cout << "Pointer to double overload\n";
}

void f(std::nullptr_t nullp)
{
   std::cout << "null pointer overload\n";
}

int main()
{
    int* pi; double* pd;

    f(pi);
    f(pd);
    f(nullptr);  // would be ambiguous without void f(nullptr_t)
    // f(NULL);  // ambiguous overload: all three functions are candidates
}

    Output: 

    Pointer to integer overload
Pointer to double overload
null pointer overload

    Vedi anche

    nullptr
    il puntatore letterale che specifica un valore nullo (C++11) valore del puntatore
    Original:
    the pointer literal which specifies a null pointer value (C++11)
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    [modifica]
    implementazione definita puntatore nullo costante
    Original:
    implementation-defined null pointer constant
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    (macro costante) [modifica]