Blog - C++ STL Algorithm accumulate()

algorithm.cpp

// addition
template <class InputIterator, class T>
T accumulate (InputIterator first, InputIterator last, T init)
{
  while (first!=last) init = init + *first++;
  return init;
}

// general Operation
template <class InputIterator, class T, Class binaryOperation>
T accumulate (InputIterator first, InputIterator last, T init, binaryOperation)
{
  while (first!=last) init = op(init, *first++);
  return init;
}

example.cpp

#include <numeric>    // for accumulate
#include <vector>         // for vector
#include <functional>     // for multiplies
#include <iostream>   // for cout

int main()
{
    std::vector<int> v;
    v.push_back(3);
    v.push_back(2);
    v.push_back(4);

    // addition
    int sum = accumulate(v.begin(), v.end(), 0);
    std::cout << "Summe: " << sum << std::endl; // Ausgabe => Summe: 9

    // Operation -> std::multiplies<int>()
    int prod = accumulate(v.begin(), v.end(), 1, std::multiplies<int>());
    std::cout << "Produkt: " << prod << std::endl; // Ausgabe => Produkt: 24
}