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std::accumulate

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Bibliothèque d'algorithmes
Fonctions
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Functions
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Non-modification de la séquence des opérations
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Non-modifying sequence operations
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Modification de la séquence des opérations
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Modifying sequence operations
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Des opérations de partitionnement
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Partitioning operations
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Opérations de tri (sur les gammes triés)
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Sorting operations (on sorted ranges)
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is_sorted (C++11)
is_sorted_until (C++11)
sort
Opérations binaires de recherche (sur les gammes triés)
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Binary search operations (on sorted ranges)
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Définir les opérations (sur les gammes triés)
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Set operations (on sorted ranges)
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Opérations Heap
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Heap operations
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Minimum / maximum de fonctionnement
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Minimum/maximum operations
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Opérations numériques
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Numeric operations
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iota (C++11)
accumulate
inner_product
Bibliothèque C
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C library
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Defined in header <numeric>
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)
Calcule la somme de la valeur donnée init et les éléments de la gamme [first, last). La première version utilise operator+ de résumer les éléments, la deuxième version utilise la fonction binaire donné op .
Original:
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.
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Sommaire

[modifier] Paramètres

first, last -
la gamme des éléments de somme
Original:
the range of elements to sum
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init -
valeur initiale de la somme
Original:
initial value of the sum
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op - binary operation function object that will be applied.

The signature of the function should be equivalent to the following:

 Ret fun(const Type1 &a, const Type2 &b);

The signature does not need to have const &.
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 InputIt can be dereferenced and then implicitly converted to  Type2. The type  Ret must be such that an object of type T can be assigned a value of type  Ret. ​

Type requirements
-
InputIt must meet the requirements of InputIterator.
-
T must meet the requirements of CopyAssignable and CopyConstructible.

[modifier] Retourne la valeur

La somme de la valeur donnée et des éléments dans la gamme proposée .
Original:
The sum of the given value and elements in the given range.
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[modifier] Mise en œuvre possible

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;
}

[modifier] Exemple

#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';
}

Résultat :

55
3628800
sssssbbbbb

[modifier] Voir aussi

calcule les différences entre les éléments adjacents dans une gamme
Original:
computes the differences between adjacent elements in a range
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(fonction générique) [edit]
calcule le produit scalaire de deux gammes d'éléments
Original:
computes the inner product of two ranges of elements
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(fonction générique) [edit]
calcule la somme partielle d'une série d'éléments
Original:
computes the partial sum of a range of elements
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(fonction générique) [edit]