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std::nullptr_t

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C++
 
Utilities-Bibliothek
 
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Grundtypen
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Basic types
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Grundtypen
Feste Breite Integer-Typen (C++11)
nullptr_t(C++11)
offsetof
NULL
Numerische Grenzen
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Numeric limits
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numeric_limits
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Type trait constants
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integral_constant(C++11)
 
definiert in Header <cstddef>
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.
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[Bearbeiten] 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.
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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

[Bearbeiten] Siehe auch

nullptr
der Zeiger wörtliche, die eine Null-Zeiger-Wert (C++11) angibt
Original:
the pointer literal which specifies a null pointer value (C++11)
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[edit]
Implementierung definiert Null-Zeiger konstant
Original:
implementation-defined null pointer constant
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(Makro konstant) [edit]
Von „https://de.cppreference.com/mwiki/index.php?title=cpp/types/nullptr_t&oldid=30268“