std::lower_bound
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<tbody> </tbody>| Dclar dans l'en-tte <algorithm>
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template< class ForwardIt, class T > ForwardIt lower_bound( ForwardIt first, ForwardIt last, const T& value ); |
(1) | |
template< class ForwardIt, class T, class Compare > ForwardIt lower_bound( ForwardIt first, ForwardIt last, const T& value, Compare comp ); |
(2) | |
Retourne un itrateur pointant sur le premier lment dans la gamme
[first, last) qui n'est pas' moins que value. La premire version utilise operator< de comparer les lments, la deuxime version utilise la fonction de comparaison donne comp .Original:
Returns an iterator pointing to the first element in the range
[first, last) that is not less than value. The first version uses operator< to compare the elements, the second version uses the given comparison function comp.The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Paramtres
| first, last | - | itrateurs dfinissant la plage d'examiner
Original: iterators defining the range to examine The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| value | - | valeur comparer les lments d'
Original: value to compare the elements to The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| comp | - | comparison function which returns true if the first argument is less than the second. The signature of the comparison function should be equivalent to the following:
The signature does not need to have |
| Type requirements | ||
-ForwardIt must meet the requirements of ForwardIterator.
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Retourne la valeur
Itrateur pointant sur le premier lment qui n'est pas moins de
value ou last si aucun lment correspondant n'est trouv .Original:
Iterator pointing to the first element that is not less than
value, or last if no such element is found.The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Complexit
Logarithmique de la distance entre
first et lastOriginal:
Logarithmic in the distance between
first and lastThe text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Mise en uvre possible
| First version |
|---|
template<class ForwardIt, class T>
ForwardIt lower_bound(ForwardIt first, ForwardIt last, const T& value)
{
ForwardIt it;
std::iterator_traits<ForwardIt>::difference_type count, step;
count = std::distance(first, last);
while (count > 0) {
it = first;
step = count / 2;
std::advance(it, step);
if (*it < value) {
first = ++it;
count -= step + 1;
} else count = step;
}
return first;
}
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| Second version |
template<class ForwardIt, class T, class Compare>
ForwardIt lower_bound(ForwardIt first, ForwardIt last, const T& value, Compare comp)
{
ForwardIt it;
std::iterator_traits<ForwardIt>::difference_type count, step;
count = std::distance(first,last);
while (count > 0) {
it = first;
step = count / 2;
std::advance(it, step);
if (comp(*it, value)),
first = ++it;
count -= step + 1;
} else count = step;
}
return first;
}
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Exemple
#include <algorithm>
#include <iostream>
#include <iterator>
#include <vector>
int main()
{
std::vector<int> data = { 1, 1, 2, 3, 3, 3, 3, 4, 4, 4, 5, 5, 6 };
auto lower = std::lower_bound(data.begin(), data.end(), 4);
auto upper = std::upper_bound(data.begin(), data.end(), 4);
std::copy(lower, upper, std::ostream_iterator<int>(std::cout, " "));
}
Rsultat :
4 4 4
Voir aussi
rendements varient d'lments correspondant une cl spcifique Original: returns range of elements matching a specific key The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction gnrique) | |
retourne un itrateur sur le premier lment' plus grande qu'une certaine valeur Original: returns an iterator to the first element greater than a certain value The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction gnrique) | |