Espaços nominais
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std::copy, std::copy_if

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< cpp‎ | algorithm

 
 
Biblioteca algoritmo
Funções
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Functions
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Não modificar operações de seqüência
Original:
Non-modifying sequence operations
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Modificando operações de seqüência
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Modifying sequence operations
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Particionamento operações
Original:
Partitioning operations
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Operações de classificação (em intervalos ordenados)
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Sorting operations (on sorted ranges)
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Binários operações de busca (em intervalos ordenados)
Original:
Binary search operations (on sorted ranges)
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Definir operações (em intervalos ordenados)
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Set operations (on sorted ranges)
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Operações de pilha
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Heap operations
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Mínimo / máximo de operações
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Minimum/maximum operations
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Operações numéricas
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Numeric operations
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C biblioteca
Original:
C library
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Defined in header <algorithm>
template< class InputIt, class OutputIt >
OutputIt copy( InputIt first, InputIt last, OutputIt d_first );
(1)
template< class InputIt, class OutputIt, class UnaryPredicate >

OutputIt copy_if( InputIt first, InputIt last,
                  OutputIt d_first,

                  UnaryPredicate pred );
(2) (a partir do C++ 11)
Copia os elementos no intervalo, definidos por [first, last), a outra no início gama d_first. A segunda função apenas copia os elementos para os quais o predicado pred retornos true.
Original:
Copies the elements in the range, defined by [first, last), to another range beginning at d_first. The second function only copies the elements for which the predicate pred returns true.
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Índice

[editar] Parâmetros

first, last -
a gama de elementos para copiar
Original:
the range of elements to copy
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d_first -
o início do intervalo de destino. Se d_first está dentro [first, last), std::copy_backward deve ser utilizado em vez de std::copy .
Original:
the beginning of the destination range. If d_first is within [first, last), std::copy_backward must be used instead of std::copy.
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pred - unary predicate which returns ​true
para os elementos necessários
Original:
for the required elements
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.

The signature of the predicate function should be equivalent to the following:

 bool pred(const Type &a);

The signature does not need to have const &, but the function must not modify the objects passed to it.
The type Type must be such that an object of type InputIt can be dereferenced and then implicitly converted to Type. ​

Type requirements
-
InputIt must meet the requirements of InputIterator.
-
OutputIt must meet the requirements of OutputIterator.

[editar] Valor de retorno

Iterator saída para o elemento da faixa de destino, um após o último elemento copiado.
Original:
Output iterator to the element in the destination range, one past the last element copied.
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[editar] Complexidade

1)
Exatamente last - first atribuições
Original:
Exactly last - first assignments
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2)
Exatamente last - first aplicações do predicado
Original:
Exactly last - first applications of the predicate
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[editar] Notas

Na prática, as implementações de std::copy evitar várias atribuições e uso em massa cópia funções como std::memcpy se o tipo de valor é TriviallyCopyable
Original:
In practice, implementations of std::copy avoid multiple assignments and use bulk copy functions such as std::memcpy if the value type is TriviallyCopyable
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[editar] Possível implementação

First version
template<class InputIt, class OutputIt>
OutputIt copy(InputIt first, InputIt last, 
              OutputIt d_first)
{
    while (first != last) {
        *d_first++ = *first++;
    }
    return d_first;
}
Second version
template<class InputIt, class OutputIt, class UnaryPredicate>
OutputIt copy_if(InputIt first, InputIt last, 
                 OutputIt d_first, UnaryPredicate pred)
{
    while (first != last) {
        if(pred(*first))
            *d_first++ = *first;
         first++;
    }
    return d_first;
}

[editar] Exemplo

O código a seguir usa cópia para a cópia do conteúdo de um vetor para outro e para exibir o vetor resultante:
Original:
The following code uses copy to both copy the contents of one vector to another and to display the resulting vector:
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#include <algorithm>
#include <iostream>
#include <vector>
#include <iterator>
 
int main()
{
    std::vector<int> from_vector;
    for (int i = 0; i < 10; i++) {
        from_vector.push_back(i);
    }
 
    std::vector<int> to_vector(10);
 
    std::copy(from_vector.begin(), from_vector.end(), to_vector.begin());
 
    std::cout << "to_vector contains: ";
    std::copy(to_vector.begin(), to_vector.end(), 
              std::ostream_iterator<int>(std::cout, " "));
    std::cout << std::endl;
}

Output:

to_vector contains: 0 1 2 3 4 5 6 7 8 9

[editar] Veja também

cópias. uma série de elementos a fim de trás
Original:
copies a range of elements in backwards order
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(modelo de função) [edit]
Copia um intervalo de elementos omitindo aqueles que satisfazem critérios específicos
Original:
copies a range of elements omitting those that satisfy specific criteria
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(modelo de função) [edit]