std::nullptr_t

 

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rel_ops::operator!= rel_ops::operator> rel_ops::operator<= rel_ops::operator>=

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ptrdiff_t size_t max_align_t (C++11)	nullptr_t (C++11) offsetof NULL
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Digitare costanti tratto Original: Type trait constants The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
integral_constant (C++11)

 

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) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
NULL	implementazione definita puntatore nullo costante Original: implementation-defined null pointer constant The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (macro costante)