std::nullptr_t
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<tbody> </tbody>| definiert in Header <cstddef>
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typedef decltype(nullptr) nullptr_t; |
(seit C++11) | |
std::nullptr_t ist die Art der Null-Zeiger Literal
nullptr . Original:
std::nullptr_t is the type of the null pointer literal,
nullptr. The text has been machine-translated via Google Translate.
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Beispiel
Wenn zwei oder mehr Überlastungen verschiedenen Zeigertypen zu akzeptieren, ist eine Überlast für std::nullptr_t notwendig, um eine Null-Zeiger-Argument akzeptieren .
Original:
If two or more overloads accept different pointer types, an overload for std::nullptr_t is necessary to accept a null pointer argument.
The text has been machine-translated via Google Translate.
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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