std::accumulate

주어진 범위의 데이터를 인자로 넘겨진 계산식으로 계산해 반환한다.

 

first	요소 범위의 시작
last	요소 범위의 끝
init	초기 값
op	적용될 한 쌍의 작업 함수 객체 (시그니처: Ret func(const Type1 &a, const Type2 &b);

 

#include <iostream>
#include <vector>
#include <numeric>
#include <string>
#include <functional>
 
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, std::multiplies<int>());
 
    auto dash_fold = [](std::string a, int b) {
                         return std::move(a) + '-' + std::to_string(b);
                     };
 
    std::string s = std::accumulate(std::next(v.begin()), v.end(),
                                    std::to_string(v[0]), // start with first element
                                    dash_fold);
 
    // Right fold using reverse iterators
    std::string rs = std::accumulate(std::next(v.rbegin()), v.rend(),
                                     std::to_string(v.back()), // start with last element
                                     dash_fold);
 
    std::cout << "sum: " << sum << '\n'
              << "product: " << product << '\n'
              << "dash-separated string: " << s << '\n'
              << "dash-separated string (right-folded): " << rs << '\n';
}

 

Output:

sum: 55
product: 3628800
dash-separated string: 1-2-3-4-5-6-7-8-9-10
dash-separated string (right-folded): 10-9-8-7-6-5-4-3-2-1

 

 

 

 

https://en.cppreference.com/w/cpp/algorithm/accumulate

std::accumulate - cppreference.com

https://en.cppreference.com/w/cpp/utility/functional/plus

std::plus - cppreference.com

https://en.cppreference.com/w/cpp/utility/functional/minus

std::minus - cppreference.com

https://en.cppreference.com/w/cpp/utility/functional/multiplies

std::multiplies - cppreference.com

https://en.cppreference.com/w/cpp/utility/functional/divides

std::divides - cppreference.com

https://en.cppreference.com/w/cpp/utility/functional/modulus

std::modulus - cppreference.com