std::copy_n
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<metanoindex/>
<tbody> </tbody>| definiert 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.
Parameter
| first | - | the beginning of the range of elements to copy from |
| count | - | number of the elements to copy |
| result | - | der Beginn des Zielbereichs
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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Rückgabewert
Iterator in the destination range, pointing past the last element copied if count>0 or first otherwise.
Komplexität
Exactly count assignments, if count>0.
Mögliche Implementierung
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;
}
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Beispiel
#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