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std::copy_n

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< cpp‎ | algorithm

 
 
アルゴリズムライブラリ
機能します
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Functions
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シーケンス動作を非改変
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Non-modifying sequence operations
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シーケンス動作を変更する
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Modifying sequence operations
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操作を仕切る
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Partitioning operations
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(ソートされた範囲で)ソート操作
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Sorting operations (on sorted ranges)
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バイナリ検索操作(ソート範囲で)
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Binary search operations (on sorted ranges)
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(ソートされた範囲で)操作を設定します
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Set operations (on sorted ranges)
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ヒープ操作
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Heap operations
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最小値/最大値操作
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Minimum/maximum operations
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数値演算
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Numeric operations
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Cライブラリ
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C library
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Defined in 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.

目次

[編集] パラメータ

first - the beginning of the range of elements to copy from
count - number of the elements to copy
result -
目的の範囲の始まり
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.

[編集] 値を返します

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

[編集] 複雑

Exactly count assignments, if count>0.

[編集] 可能な実装

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;
}

[編集]

#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

[編集] も参照してください

新しい場所に要素の範囲をコピーします
Original:
copies a range of elements to a new location
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(関数テンプレート) [edit]