std::lower_bound

 

C++

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Espressioni regolari (C++11)

Operazioni atomicche (C++11)

Multithreading (C++11)

 

Algoritmo libreria

Funzioni Original: Functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
Non modifica le operazioni di sequenza Original: Non-modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
all_of any_of none_of (C++11) (C++11) (C++11) for_each count count_if mismatch equal	find find_if find_if_not (C++11) find_end find_first_of adjacent_find search search_n
Modifica delle operazioni di sequenza Original: Modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
copy copy_if (C++11) copy_n (C++11) copy_backward move (C++11) move_backward (C++11) fill fill_n transform generate generate_n remove remove_if remove_copy remove_copy_if	replace replace_if replace_copy replace_copy_if swap swap_ranges iter_swap reverse reverse_copy rotate rotate_copy random_shuffle shuffle   (C++11) unique unique_copy
Partizionamento operazioni Original: Partitioning operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_partitioned (C++11) partition partition_copy (C++11)	stable_partition partition_point (C++11)
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is_sorted (C++11) is_sorted_until (C++11) sort	partial_sort partial_sort_copy stable_sort nth_element
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lower_bound upper_bound	binary_search equal_range
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merge inplace_merge includes	set_difference set_intersection set_symmetric_difference set_union
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max max_element min min_element minmax (C++11) minmax_element (C++11)	lexicographical_compare is_permutation (C++11) next_permutation prev_permutation
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qsort	bsearch

 

Defined in header <algorithm>
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)

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.

Parametri

first, last	-	iterators defining the range to examine
value	-	valore per confrontare gli elementi 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 ForwardIt can be dereferenced and then implicitly converted to Type1. The type Type2 must be such that an object of type T can be implicitly converted to Type2. ​
Type requirements
- ForwardIt must meet the requirements of ForwardIterator.

Valore di ritorno

Iterator pointing to the first element that is not less than value, or last if no such element is found.

Complessità

Logaritmica della distanza tra first e last

Original:

Logarithmic in the distance between first and last

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Possibile implementazione

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; }
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; }

Esempio

#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, " "));
}

Output:

4 4 4

Vedi anche

equal_range	torna gamma di elementi che corrispondono un tasto specifico 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. (funzione di modello)
upper_bound	ritorna un iteratore al primo elemento' maggiore di un certo valore 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. (funzione di modello)