std::copy_n
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| Defined in header <algorithm>
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| template< class InputIt, class Size, class OutputIt > OutputIt copy_n( InputIt first, Size count, OutputIt result ); |
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Copies exactly count values from the range beginning at first to the range beginning at result, if count>0. Does nothing otherwise.
目录 |
[编辑] 参数
| first | - | the beginning of the range of elements to copy from |
| count | - | number of the elements to copy |
| result | - | 的目标范围的开头
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.
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-OutputIt must meet the requirements of OutputIterator.
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[编辑] 返回值
Iterator in the destination range, pointing past the last element copied if count>0 or first otherwise.
[编辑] 复杂性
Exactly count assignments, if count>0.
[编辑] 可能的实现
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; } |
[编辑] 为例
#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
[编辑] 另请参阅
| （C++11） |
某一范围的元素复制到一个新的位置 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. （函数模板） |
