std::accumulate
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<metanoindex/>
<tbody> </tbody>| Elemento definito nell'header <numeric>
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template< class InputIt, class T > T accumulate( InputIt first, InputIt last, T init ); |
(1) | |
template< class InputIt, class T, class BinaryOperation > T accumulate( InputIt first, InputIt last, T init, BinaryOperation op ); |
(2) | |
Computes the sum of the given value init and the elements in the range [first, last). The first version uses operator+ to sum up the elements, the second version uses the given binary function op.
Parametri
| first, last | - | l'intervallo di elementi di somma
Original: the range of elements to sum The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| init | - | initial value of the sum |
| op | - | binary operation function object that will be applied. The signature of the function should be equivalent to the following:
The signature does not need to have |
| Type requirements | ||
-InputIt must meet the requirements of InputIterator.
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-T must meet the requirements of CopyAssignable and CopyConstructible.
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Valore di ritorno
The sum of the given value and elements in the given range.
Possibile implementazione
| First version |
|---|
template<class InputIt, class T>
T accumulate(InputIt first, InputIt last, T value)
{
for (; first != last; ++first) {
value = value + *first;
}
return value;
}
|
| Second version |
template<class InputIt, class T, class BinaryOperation>
T accumulate(InputIt first, InputIt last, T value,
BinaryOperation op)
{
for (; first != last; ++first) {
value = op(value, *first);
}
return value;
}
|
Esempio
#include <iostream>
#include <vector>
#include <numeric>
#include <string>
int multiply(int x, int y)
{
return x*y;
}
std::string magic_function(std::string res, int x)
{
return res += (x > 5) ? "b" : "s";
}
int main()
{
std::vector<int> v{1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
int sum = std::accumulate(v.begin(), v.end(), 0);
int product = std::accumulate(v.begin(), v.end(), 1, multiply);
std::string magic = std::accumulate(v.begin(), v.end(), std::string(),
magic_function);
std::cout << sum << '\n'
<< product << '\n'
<< magic << '\n';
}
Output:
55
3628800
sssssbbbbb
Vedi anche
calcola le differenze tra elementi adiacenti in un intervallo Original: computes the differences between adjacent elements in a range 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 il prodotto interno di due gamme di elementi Original: computes the inner product of two ranges 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) | |