std::lower_bound
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| Elemento definito nell'header <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) | |
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.
Indice |
[modifica] 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. |
| Type requirements | ||
-ForwardIt must meet the requirements of ForwardIterator.
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[modifica] Valore di ritorno
Iterator pointing to the first element that is not less than value, or last if no such element is found.
[modifica] Complessità
first e lastfirst and lastYou can help to correct and verify the translation. Click here for instructions.
[modifica] Possibile implementazione
| First version |
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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; } |
[modifica] 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
[modifica] Vedi anche
| 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) | |
| 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) | |
