std::upper_bound - cppreference.com

std::upper_bound

Da cppreference.com.

<metanoindex/>

 
C++
 
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.
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.
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.
Ordinamento delle operazioni (su intervalli ordinati)
Original:
Sorting operations (on sorted ranges)
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Binarie (le operazioni di ricerca sui campi ordinati)
Original:
Binary search operations (on sorted ranges)
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Impostare le operazioni (su intervalli ordinati)
Original:
Set operations (on sorted ranges)
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Heap operazioni
Original:
Heap operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Minimo / massimo le operazioni
Original:
Minimum/maximum operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Operazioni numeriche
Original:
Numeric operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Libreria C
Original:
C library
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
 
<tbody> </tbody>
Elemento definito nell'header <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)
Restituisce un iteratore che punta al primo elemento della [first, last) gamma che è superiore rispetto value. La prima versione utilizza operator< di confrontare gli elementi, la seconda versione utilizza la funzione di confronto dato 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.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Parametri

first, last -
la gamma di elementi da esaminare
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 -
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 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.

Valore di ritorno

iteratore che punta al primo elemento che è superiore di value, o last se tale elemento non viene trovato.
Original:
iterator pointing to the first element that is greater 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.

Possibile implementazione

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;
}

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

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.

Vedi anche