std::upper_bound — cppreference.com

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Déclaré dans l'en-tête `<algorithm>`
`template< class ForwardIt, class T > ForwardIt upper_bound( ForwardIt first, ForwardIt last, const T& value );`	(1)
`template< class ForwardIt, class T, class Compare > ForwardIt upper_bound( ForwardIt first, ForwardIt last, const T& value, Compare comp );`	(2)

Retourne un itérateur pointant sur le premier élément de la [first, last) plage qui est plus que value. La première version utilise operator< de comparer les éléments, la deuxième version utilise la fonction de comparaison donnée comp .

Original:

Returns an iterator pointing to the first element in the range [first, last) that is greater than value. The first version uses operator< to compare the elements, the second version uses the given comparison function comp.

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Paramètres

first, last	-	l'éventail des éléments à examiner Original: the range of elements 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 à comparer les éléments 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: `bool cmp(const Type1 &a, const Type2 &b);` The signature does not need to have `const &`, but the function must not modify the objects passed to it. The type `Type1` must be such that an object of type `T` can be implicitly converted to `Type1`. The type `Type2` must be such that an object of type `ForwardIt` can be dereferenced and then implicitly converted to `Type2`.
Type requirements
-`ForwardIt` must meet the requirements of `ForwardIterator`.

Retourne la valeur

itérateur pointant sur le premier élément qui est plus que value ou last si aucun élément correspondant n'est trouvé .

Original:

iterator pointing to the first element that is greater than value, or last if no such element is found.

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Mise en œuvre possible

First version
template<class ForwardIt, class T> ForwardIt upper_bound(ForwardIt first, ForwardIt last, const T& value) { ForwardIt it; std::iterator_traits<ForwardIt>::distance_type count, step; count = std::distance(first,last); while (count > 0) { it = first; step = count / 2; std::advance(it, step); if (!(value < *it)) { first = ++it; count -= step + 1; } else count = step; } return first; }
Second version
template<class ForwardIt, class T, class Compare> ForwardIt upper_bound(ForwardIt first, ForwardIt last, const T& value, Compare comp) { ForwardIt it; std::iterator_traits<ForwardIt>::distance_type count, step; count = std::distance(first,last); while (count > 0) { it = first; step = count / 2; std::advance(it, step); if (!comp(value, *it)), first = ++it; count -= step + 1 } else count = step; } return first; }

First version

template<class ForwardIt, class T>
ForwardIt upper_bound(ForwardIt first, ForwardIt last,
                            const T& value)
{
    ForwardIt it;
    std::iterator_traits<ForwardIt>::distance_type count, step;
    count = std::distance(first,last);

    while (count > 0) {
        it = first; 
        step = count / 2; 
        std::advance(it, step);
        if (!(value < *it)) {
            first = ++it;
            count -= step + 1;
        } else count = step;
    }
    return first;
}

Second version

template<class ForwardIt, class T, class Compare>
ForwardIt upper_bound(ForwardIt first, ForwardIt last,
                            const T& value, Compare comp)
{
    ForwardIt it;
    std::iterator_traits<ForwardIt>::distance_type count, step;
    count = std::distance(first,last);

    while (count > 0) {
        it = first; 
        step = count / 2;
        std::advance(it, step);
        if (!comp(value, *it)),
            first = ++it;
            count -= step + 1
        } else count = step;
    }
    return first;
}

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, " "));
}

Résultat :

Complexité

logarithmique de la distance entre first et last

Original:

logarithmic in the distance between first and last

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Voir aussi


	rendements varient d'éléments correspondant à une clé spécifique 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 générique) [edit]

	retourne un itérateur sur le premier élément' pas moins que la valeur donnée Original: *returns an iterator to the first element not less* than the given value The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction générique) [edit]**