std::copy, std::copy_if
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| Definido no cabeçalho <algorithm>
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| 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, |
(2) | (desde 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. The text has been machine-translated via Google Translate.
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Índice |
[editar] Parâmetros
| first, last | - | a gama de elementos para copiar
Original: the range of elements to copy The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| 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. The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| pred | - | unary predicate which returns true para os elementos necessários . Original: for the required elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. 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. |
| Type requirements | ||
-InputIt must meet the requirements of InputIterator.
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-OutputIt must meet the requirements of OutputIterator.
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[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
2) last - first atribuiçõesOriginal:
Exactly
last - first assignmentsThe text has been machine-translated via Google Translate.
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Exatamente
last - first aplicações do predicadoOriginal:
Exactly
last - first applications of the predicateThe text has been machine-translated via Google Translate.
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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 TriviallyCopyableOriginal:
In practice, implementations of
std::copy avoid multiple assignments and use bulk copy functions such as std::memcpy if the value type is TriviallyCopyableThe text has been machine-translated via Google Translate.
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[editar] Possível implementação
| First version |
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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; }
Saída:
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 The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de função) | |
| Copia um intervalo de elementos omitindo aqueles que satisfazem critérios específicos Original: copies a range of elements omitting those that satisfy specific criteria The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de função) | |
