std::partition
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<metanoindex/>
<tbody> </tbody>| Déclaré dans l'en-tête <algorithm>
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template< class BidirIt, class UnaryPredicate > BidirectionalIterator partition( BidirIt first, BidirIt last, UnaryPredicate p ); template< class ForwardIt, class UnaryPredicate > ForwardIt partition( ForwardIt first, ForwardIt last, UnaryPredicate p ); |
(avant C++11) (depuis C++11) |
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Réordonne les éléments de la gamme
[first, last) de telle manière que tous les éléments pour lesquels le prédicat renvoie p true précèdent les éléments pour lesquels prédicat retourne p false. Ordre relatif des éléments ne sont pas conservées . Original:
Reorders the elements in the range
[first, last) in such a way that all elements for which the predicate p returns true precede the elements for which predicate p returns false. Relative order of the elements is not preserved. The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
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Paramètres
| first, last | - | l'éventail d'éléments à réorganiser
Original: the range of elements to reorder The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| p | - | prédicat unéaire qui retourne true si l'élément doit être commandé avant autres éléments . Original: if the element should be ordered before other elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. L'expression |
| Type requirements | ||
-BidirIt must meet the requirements of BidirectionalIterator.
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-ForwardIt must meet the requirements of ValueSwappable and ForwardIterator. However, the operation is more efficient if ForwardIt also satisfies the requirements of BidirectionalIterator
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Retourne la valeur
Itérateur sur le premier élément du second groupe .
Original:
Iterator to the first element of the second group.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
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Complexité
Exactement
last-first applications du prédicat et à la plupart des swaps last-first. Si ForwardIt répond aux exigences de la plupart des swaps BidirectionalIterator à (last-first)/2 sont fait .Original:
Exactly
last-first applications of the predicate and at most last-first swaps. If ForwardIt meets the requirements of BidirectionalIterator at most (last-first)/2 swaps are done.The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
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Mise en œuvre possible
template<class BidirIt, class UnaryPredicate>
BidirIt partition(BidirIt first, BidirIt last, UnaryPredicate p)
{
while (1) {
while ((first != last) && p(*first)) {
++first;
}
if (first == last--) break;
while ((first != last) && !p(*last)) {
--last;
}
if (first == last) break;
std::swap(*first++, *last);
}
return first;
}
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Exemple
#include <algorithm>
#include <functional>
#include <iostream>
#include <iterator>
#include <vector>
bool is_even(int i) { return i % 2 == 0; }
int main()
{
std::vector<int> v;
for (int i = 0; i < 10; ++i) v.push_back(i);
std::cout << "Original vector:\n ";
std::copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));
// Partition the vector
std::vector<int>::iterator p =
std::partition(v.begin(), v.end(), std::ptr_fun(is_even));
std::cout << "\nPartitioned vector:\n ";
std::copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));
std::cout << "\nBefore partition:\n ";
std::copy(v.begin(), p, std::ostream_iterator<int>(std::cout, " "));
std::cout << "\nAfter partition:\n ";
std::copy(p, v.end(), std::ostream_iterator<int>(std::cout, " "));
}
Résultat possible :
Original vector:
0 1 2 3 4 5 6 7 8 9
Partitioned vector:
0 8 2 6 4 5 3 7 1 9
Before partition:
0 8 2 6 4
After partition:
5 3 7 1 9
Voir aussi
(C++11) |
détermine si l'intervalle est divisé par le prédicat donné Original: determines if the range is partitioned by the given predicate The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction générique) |
divise les éléments en deux groupes, tout en préservant leur ordre relatif Original: divides elements into two groups while preserving their relative order The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction générique) | |