std::is_union - cppreference.com

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Definido no cabeçalho `<type_traits>`

`template< class T > struct is_union;`		(desde C++11)

Se T é um tipo de união, fornece o membro constante value true igual. Para qualquer outro tipo, é value false.

Original:

If T is a union type, provides the member constant value equal true. For any other type, value is false.

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Herdado de std::integral_constant

Member constants


	`true` se `T` is a union type , `false` contrário Original: `true` if `T` is a union type , `false` otherwise The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (membro estático público constante)

Member functions


	converte o objeto em `bool`, retorna `value` Original: converts the object to `bool`, returns `value` The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (função pública membro)

Member types


Tipo Original: Type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.	Definition

`value_type`	`bool`

`type`	`std::integral_constant<bool, value>`

Exemplo

#include <iostream>
#include <type_traits>

struct A {};

typedef union {
    int a;
    float b;
} B;

struct C {
    B d;
};

int main() 
{
    std::cout << std::boolalpha;
    std::cout << std::is_union<A>::value << '\n';
    std::cout << std::is_union<B>::value << '\n';
    std::cout << std::is_union<C>::value << '\n';
    std::cout << std::is_union<int>::value << '\n';
}

Saída:

Veja também


	checks if a type is a class type (but not union type) (modelo de classe) [edit]