alignof operator (desde C++11)
De cppreference.com
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Consultas alinhamento requisitos de um tipo
Original:
Queries alignment requirements of a type
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Sintaxe
alignof( type )
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Retorna um objeto do tipo std::size_t.
Original:
Returns an object of type std::size_t.
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Explicação
Retorna o alinhamento em bytes (uma potência inteira de dois) necessário para qualquer instância do
type dado, que é um ou outro tipo completo, um tipo de matriz, ou um tipo de referência.Original:
Returns alignment in bytes (an integer power of two) required for any instance of the given
type, which is either complete type, an array type, or a reference type.The text has been machine-translated via Google Translate.
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Se o tipo é tipo de referência, o operador retorna o alinhamento de referência tipo, se o tipo é tipo de matriz, exigência de alinhamento do tipo de elemento é retornado.
Original:
If the type is reference type, the operator returns the alignment of referenced type; if the type is array type, alignment requirement of the element type is returned.
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Os tipos
char, signed char e unsigned char ter mais fraco alinhamento (menor) suportado pela implementação.Original:
The types
char, signed char, and unsigned char have the weakest (smallest) alignment supported by the implementation.The text has been machine-translated via Google Translate.
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Palavras-chave
Exemplo
#include <iostream>
struct Empty {};
struct Foo {
int f2;
float f1;
char c;
};
int main()
{
std::cout << "alignment of empty class: " << alignof(Empty) << '\n'
<< "alignment of pointer : " << alignof(int*) << '\n'
<< "alignment of char : " << alignof(char) << '\n'
<< "alignment of Foo : " << alignof(Foo) << '\n' ;
}
Saída:
alignment of empty class: 1
alignment of pointer : 8
alignment of char : 1
alignment of Foo : 4