std::inner_product
Da cppreference.com.
 |
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. |
<metanoindex/>
<tbody> </tbody>| Elemento definito nell'header <numeric>
|
||
template< class InputIt1, class InputIt2, class T > T inner_product( InputIt1 first1, InputIt1 last1, InputIt2 first2, T value ); |
(1) | |
template< class InputIt1, class InputIt2, class T, class BinaryOperation1, class BinaryOperation2 > T inner_product( InputIt1 first1, InputIt1 last1, InputIt2 first2, T value, BinaryOperation1 op1, BinaryOperation2 op2 ); |
(2) | |
Calcola prodotto interno (ossia la somma dei prodotti) del
[first1, last1) gamma e un altro inizio gamma a first2. La prima versione utilizza per calcolare operator* prodotto delle coppie di elementi e operator+ per riassumere i prodotti, la seconda versione utilizza op2 e op1 per questi compiti, rispettivamente.Original:
Computes inner product (i.e. sum of products) of the range
[first1, last1) and another range beginning at first2. The first version uses operator* to compute product of the element pairs and operator+ to sum up the products, the second version uses op2 and op1 for these tasks respectively.The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Parametri
| first1, last1 | - | la prima serie di elementi
Original: the first range of elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| first2 | - | all'inizio del secondo intervallo di elementi
Original: the beginning of the second range of elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| value | - | valore iniziale della somma dei prodotti
Original: initial value of the sum of the products The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| op1 | - | binary operation function object that will be applied. Questa funzione prende un valore restituito da op2 e il valore corrente dell'accumulatore e produce un nuovo valore da memorizzare nell'accumulatore . Original: This function takes a value returned by op2 and the current value of the accumulator and produces a new value to be stored in the accumulator. The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. The signature of the function should be equivalent to the following:
The signature does not need to have |
| op2 | - | binary operation function object that will be applied. Questa funzione prende un valore da ogni intervallo e produce un nuovo valore . Original: This function takes one value from each range and produces a new value. The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. The signature of the function should be equivalent to the following:
The signature does not need to have |
| Type requirements | ||
-InputIt1, InputIt2 must meet the requirements of InputIterator.
| ||
-T must meet the requirements of CopyAssignable and CopyConstructible.
| ||
Valore di ritorno
Il prodotto interno di due intervalli.
Original:
The inner product of two ranges.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Possibile implementazione
| First version |
|---|
template<class InputIt1, class InputIt2, class T>
T inner_product(InputIt1 first1, InputIt1 last1,
InputIt2 first2, T value)
{
while (first1 != last1) {
value = value + *first1 * *first2;
++first1;
++first2;
}
return value;
}
|
| Second version |
template<class InputIt1, class InputIt2,
class T,
class BinaryOperation1, class BinaryOperation2>
T inner_product(InputIt1 first1, InputIt1 last1,
InputIt2 first2, T value,
BinaryOperation1 op1
BinaryOperation2 op2)
{
while (first1 != last1) {
value = op1(value, op2(*first1, *first2));
++first1;
++first2;
}
return value;
}
|
Esempio
#include <numeric>
#include <iostream>
#include <vector>
#include <functional>
int main()
{
std::vector<int> a{0, 1, 2, 3, 4};
std::vector<int> b{5, 4, 2, 3, 1};
int r1 = std::inner_product(a.begin(), a.end(), b.begin(), 0);
std::cout << "Inner product of a and b: " << r1 << '\n';
int r2 = std::inner_product(a.begin(), a.end(), b.begin(), 0,
std::plus<int>(), std::equal_to<int>());
std::cout << "Number of pairwise matches between a and b: " << r2 << '\n';
}
Output:
Inner product of a and b: 21
Number of pairwise matches between a and b: 2
Vedi anche
riassume una serie di elementi Original: sums up a range of 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) | |
calcola la somma parziale di una serie di elementi Original: computes the partial sum of a range of 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) | |