Espaços nominais
Variantes
Acções

offsetof

Da cppreference.com
< cpp‎ | types

This page has been machine-translated from the English version of the wiki using Google Translate.

The translation may contain errors and awkward wording. Hover over text to see the original version. You can help to fix errors and improve the translation. For instructions click here.

Click here for the English version of this page

 
C++
 
Biblioteca de utilitários
Digite apoio (basic types, RTTI, type traits)
Gerenciamento de memória dinâmica
De tratamento de erros
Utilidades do programa
Variadic funções
Data e hora
Objetos de função
(C++11)
(C++11)
Os operadores relacionais
Original:
Relational operators
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
rel_ops::operator!=
rel_ops::operator>
rel_ops::operator<=
rel_ops::operator>=
Pares e tuplas
Original:
Pairs and tuples
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
(C++11)
(C++11)
(C++11)
Troque, avançar e avançar
Original:
Swap, forward and move
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
(C++11)
(C++11)
(C++11)
(C++11)
 
Apoio a tipos
Tipos básicos
Original:
Basic types
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Tipos fundamentais
Tipos inteiros de largura fixos (C++11)
(C++11)
offsetof
Limites numéricos
Original:
Numeric limits
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
C numérico limita interface
Informações de tipo de tempo de execução
Original:
Runtime type information
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Características de tipo
Original:
Type traits
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Principais categorias de tipo
Original:
Primary type categories
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Propriedades de tipo
Original:
Type properties
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Operações apoiadas
Original:
Supported operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
(C++11)(C++11)(C++11)
(C++11)(C++11)(C++11)
(C++11)(C++11)(C++11)
(C++11)(C++11)(C++11)
(C++11)(C++11)(C++11)
(C++11)(C++11)(C++11)
(C++11)(C++11)(C++11)
(C++11)(C++11)(C++11)
(C++11)
Relacionamentos e consultas de propriedade
Original:
Relationships and property queries
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Tipo modificações
Original:
Type modifications
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
(C++11)(C++11)(C++11)
(C++11)(C++11)(C++11)
(C++11)
(C++11)
Transformações tipo
Original:
Type transformations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Digite constantes traço
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.
(C++11)
 
Definido no cabeçalho <cstddef>
#define offsetof(type, member) /*implementation-defined*/
O offsetof macro expande para uma constante de std::size_t tipo, cujo valor é o deslocamento, em bytes, a partir do início de um objecto do tipo especificado para o seu membro especificado, incluindo estofamento, se qualquer.
Original:
The macro offsetof expands to a constant of type std::size_t, the value of which is the offset, in bytes, from the beginning of an object of specified type to its specified member, including padding if any.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Índice

[editar] Notas

Se type não é um tipo padrão de layout, o comportamento é indefinido.
Original:
If type is not a standard-layout type, the behavior is undefined.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Se member é um membro estático ou um membro da função, o comportamento é indefinido.
Original:
If member is a static member or a function member, the behavior is undefined.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
O deslocamento do primeiro membro de um tipo padrão de layout é sempre zero (empty-base de otimização é obrigatório)
Original:
The offset of the first member of a standard-layout type is always zero (empty-base de otimização is mandatory)
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[editar] Possível implementação

#define offsetof(type,member) ((std::size_t) &(((type*)0)->member))

[editar] Exemplo

#include <iostream>
#include <cstddef>
struct S {
    char c;
    double d;
};
int main()
{
    std::cout << "the first element is at offset " << offsetof(S, c) << '\n'
              << "the double is at offset " << offsetof(S, d) << '\n';
}

Saída: 

the first element is at offset 0
the double is at offset 8

[editar] Veja também
tipo inteiro sem sinal retornado pelo operador sizeof
Original:
unsigned integer type returned by the sizeof operator
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(typedef) [edit]
(C++11)
verifica se um tipo é o layout padrão tipo
Original:
checks if a type is standard-layout type
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(modelo de classe) [edit]
Obtida de "https://pt.cppreference.com/mwiki/index.php?title=cpp/types/offsetof&oldid=24627"