std::copy_n - cppreference.com

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Definido no cabeçalho `<algorithm>`

`template< class InputIt, class Size, class OutputIt > OutputIt copy_n( InputIt first, Size count, OutputIt result );`

Copies exactly count values from the range beginning at first to the range beginning at result, if count>0. Does nothing otherwise.

Parâmetros

first	-	the beginning of the range of elements to copy from
count	-	number of the elements to copy
result	-	o início do intervalo de destino Original: the beginning of the destination range The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
Type requirements
-`InputIt` must meet the requirements of `InputIterator`.
-`OutputIt` must meet the requirements of `OutputIterator`.

Valor de retorno

Iterator in the destination range, pointing past the last element copied if count>0 or first otherwise.

Complexidade

Exactly count assignments, if count>0.

Possível implementação

template< class InputIt, class Size, class OutputIt>
OutputIt copy_n(InputIt first, Size count, OutputIt result)
{
    if (count > 0) {
        *result++ = *first;
        for (Size i = 1; i < count; ++i) {
            *result++ = *++first;
        }
    }
    return result;
}

Exemplo

#include <iostream>
#include <string>
#include <algorithm>
#include <iterator>

int main()
{
    std::string in = "1234567890";
    std::string out;

    std::copy_n(in.begin(), 4, std::back_inserter(out));
    std::cout << out << '\n';
}

Saída:

Veja também


	Copia um intervalo de elementos para um novo local Original: copies a range of elements to a new location 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) [edit]