Varianti

    std::copy_n

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    <tbody> </tbody>
    Elemento definito nell'header <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.

    Parametri

    first - the beginning of the range of elements to copy from
    count - number of the elements to copy
    result -
    l'inizio del campo di destinazione
    Original:
    the beginning of the destination range
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    Type requirements
    -
    InputIt must meet the requirements of InputIterator.
    -
    OutputIt must meet the requirements of OutputIterator.

    Valore di ritorno

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

    Complessità

    Exactly count assignments, if count>0.

    Possibile implementazione

    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;
}

    Esempio

    #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';
}

    Output: 

    1234

    Vedi anche


    (C++11)
    copia un intervallo di elementi in una nuova posizione
    Original:
    copies a range of elements to a new location
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    (funzione di modello) [modifica]