Namespace
Varianti

std::merge

Da cppreference.com.
< cpp‎ | algorithm

Questa pagina è stata tradotta in modo automatico dalla versione in ineglese della wiki usando Google Translate.

La traduzione potrebbe contenere errori e termini strani. Muovi il puntatore sopra al testo per vedere la versione originale. Puoi aiutarci a correggere gli gli errori. Per ulteriori istruzioni clicca qui.

Click here for the English version of this page

 
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.
 
Elemento definito nell'header <algorithm>
template< class InputIt1, class InputIt2, class OutputIt >

OutputIt merge( InputIt1 first1, InputIt1 last1,
                InputIt2 first2, InputIt2 last2

                OutputIt d_first );
 (1)
template< class InputIt1, class InputIt2, class OutputIt, class Compare>

OutputIt merge( InputIt1 first1, InputIt1 last1,
                InputIt2 first2, InputIt2 last2

                OutputIt d_first, Compare comp );
 (2)
Unisce due gamme filtrate [first1, last1) e [first2, last2) in un unico campo di inizio smistati d_first. La prima versione utilizza operator< di confrontare gli elementi, la seconda versione utilizza la data comp funzione di confronto. L'ordine relativo degli elementi equivalenti è conservato.
Original:
Merges two sorted ranges [first1, last1) and [first2, last2) into one sorted range beginning at d_first. The first version uses operator< to compare the elements, the second version uses the given comparison function comp. The relative order of equivalent elements is preserved.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Indice

[modifica] Parametri

first1, last1 -
la prima gamma di elementi da unire
Original:
the first range of elements to merge
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
first2, last2 -
il secondo intervallo di elementi da unire
Original:
the second range of elements to merge
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
d_first -
l'inizio del campo di destinazione
Original:
the beginning of the destination range
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 types Type1 and Type2 must be such that objects of types InputIt1 and InputIt2 can be dereferenced and then implicitly converted to Type1 and Type2 respectively. ​

Type requirements
-
InputIt1 must meet the requirements of InputIterator.
-
InputIt2 must meet the requirements of InputIterator.
-
OutputIt must meet the requirements of OutputIterator.

[modifica] Valore di ritorno

Un iteratore di uscita all'elemento oltre l'ultimo elemento copiato.
Original:
An output iterator to element past the last element copied.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[modifica] Complessità

A confronto la maggior parte std::distance(first1, last1) + std::distance(first2, last2) + 1.
Original:
At most std::distance(first1, last1) + std::distance(first2, last2) + 1 comparisons.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[modifica] Possibile implementazione

First version 
template<class InputIt1, class InputIt2, class OutputIt>
OutputIt merge(InputIt1 first1, InputIt1 last1,
               InputIt2 first2, InputIt2 last2,
               OutputIt d_first)
{
    for (; first1 != last1; ++d_first) {
        if (first2 == last2) {
            return std::copy(first1, last1, d_first);
        }
        if (*first2 < *first1) {
            *d_first = *first2;
            ++first2;
        } else {
            *d_first = *first1;
            ++first1;
        }
    }
    return std::copy(first2, last2, d_first);
}
Second version 
template<class InputIt1, class InputIt2,
         class OutputIt, class Compare>
OutputIt merge(InputIt1 first1, InputIt1 last1,
               InputIt2 first2, InputIt2 last2,
               OutputIt d_first, Compare comp)
{
    for (; first1 != last1; ++d_first) {
        if (first2 == last2) {
            return std::copy(first1, last1, d_first);
        }
        if (comp(*first2, *first1)) {
            *d_first = *first2;
            ++first2;
        } else {
            *d_first = *first1;
            ++first1;
        }
    }
    return std::copy(first2, last2, d_first);
}

[modifica] Esempio

#include <iostream>
#include <iterator>
#include <cstdlib>
#include <algorithm>
#include <vector>
 
int main() 
{
    const std::size_t items = 10;
 
    std::vector<int> v1, v2, dst;
 
    // fill the vectors
    for (std::size_t idx = 0; idx < items; ++idx) {
        v1.push_back(std::rand()%items);
        v2.push_back(std::rand()%items);
    }
 
    // sort
    std::sort(v1.begin(), v1.end());
    std::sort(v2.begin(), v2.end());
 
    // output v1
    std::cout << "v1 : ";
    std::copy(v1.begin(), v1.end(),
              std::ostream_iterator<int>(std::cout, " "));
    std::cout << '\n';
 
    // output v2
    std::cout << "v2 : ";
    std::copy(v2.begin(), v2.end(),
              std::ostream_iterator<int>(std::cout, " "));
    std::cout << '\n';
 
    // merge
    std::merge(v1.begin(), v1.end(),
               v2.begin(), v2.end(),
               std::back_inserter(dst));
 
    // output
    std::cout << "dst: ";
    std::copy(dst.begin(), dst.end(),
             std::ostream_iterator<int>(std::cout, " "));
    std::cout << '\n';
}

Output: 

v1 : 0 0 2 2 3 3 3 6 7 9 
v2 : 1 2 5 5 6 6 6 6 7 9 
dst: 0 0 1 2 2 2 3 3 3 5 5 6 6 6 6 6 7 7 9 9

[modifica] Vedi anche
unisce due gamme ordinate in-place
Original:
merges two ordered ranges in-place
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) [modifica]
ordina una serie in ordine crescente
Original:
sorts a range into ascending order
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) [modifica]
Ordina un intervallo di elementi, mantenendo ordine tra elementi uguali
Original:
sorts a range of elements while preserving order between equal elements
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) [modifica]
Estratto da "https://it.cppreference.com/mwiki/index.php?title=cpp/algorithm/merge&oldid=24957"