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std::ignore

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< cpp‎ | utility‎ | tuple

 
 
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initializer_list(C++11)
bitset
hash(C++11)
Os operadores relacionais
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Relational operators
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rel_ops::operator!=
rel_ops::operator>
rel_ops::operator<=
rel_ops::operator>=
Pares e tuplas
Original:
Pairs and tuples
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pair
tuple(C++11)
piecewise_construct_t(C++11)
piecewise_construct(C++11)
Troque, avançar e avançar
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Swap, forward and move
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swap
forward(C++11)
move(C++11)
move_if_noexcept(C++11)
declval(C++11)
 
std::tuple
Funções de membro
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Member functions
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tuple::tuple
tuple::operator=
tuple::swap
Não-membros funções
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Non-member functions
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make_tuple
tie
forward_as_tuple
None
operator=
operator!=
operator<
operator<=
operator>
operator>=
std::swap
get
Classes auxiliares
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Helper classes
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tuple_size
tuple_element
uses_allocator
ignore
 
Defined in header <tuple>
const /*unspecified*/ ignore;
(a partir do C++ 11)
Um objeto do tipo não especificado de tal forma que qualquer valor pode ser atribuído a ele sem nenhum efeito. Projetado para uso com std::tie quando descompactar um std::tuple, como um espaço reservado para os argumentos que não são usados ​​.
Original:
An object of unspecified type such that any value can be assigned to it with no effect. Intended for use with std::tie when unpacking a std::tuple, as a placeholder for the arguments that are not used.
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[editar] Exemplo

desempacotar um par retornado por set.insert (), mas só guardar o booleano .
Original:
unpack a pair returned by set.insert(), but only save the boolean.
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#include <iostream>
#include <string>
#include <set>
#include <tuple>
 
int main()
{
    std::set<std::string> set_of_str;
    bool inserted;
    std::tie(std::ignore, inserted) = set_of_str.insert("Test");
    if (inserted) {
        std::cout << "Value was inserted sucessfully\n";
    }
}

Output:

Value was inserted sucessfully
cria um tuple de referências lvalue ou desempacota a tupla em objetos individuais
Original:
creates a tuple of lvalue references or unpacks a tuple into individual objects
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(modelo de função) [edit]