Is it possible to add all of a vector's numbers using and ?

Question

I have been looking at this problem for a day now but I cannot seem to find the answer. I need to use and to add all of the elements of a vector.

So far I found http://www.cplusplus.com/reference/functional/plus/ Is it possible to instead of adding 2 vector add its elements together? I can't find anything else that even comes close to doing what I want to do.

By the way I am new to the language. I don't need the code but just a hint in the right direction.

[`std::accumulate`](http://en.cppreference.com/w/cpp/algorithm/accumulate) — jaggedSpire, Jan 10 '17 at 16:47
aahh oke because it wasn't between these http://www.cplusplus.com/reference/algorithm/. — anonymous-dev, Jan 10 '17 at 16:48
If you would be so kind to explain us why it's so important that functions of the headers `` and `` are used we may be able to help you furthe — realvictorprm, Jan 10 '17 at 17:03
@ArthurP.R. He's been working on a homework assignment for the past few days that seems to have the constraint that you can only use `` and ``. — jaggedSpire, Jan 10 '17 at 17:20
@jaggedSpire Thanks for this information. People luckily already answered his question. — realvictorprm, Jan 10 '17 at 17:23
@MikeOttink is the constraint that you can only use the `` and `` *headers,* or does it say algorithms *library?* The algorithms library is listed [here](http://en.cppreference.com/w/cpp/algorithm) and includes ``, `` and parts of `` and ``. — jaggedSpire, Jan 10 '17 at 17:24
It literally says "Use functions from and ". I did find numeric also but it is not a function from algorithm right? — anonymous-dev, Jan 10 '17 at 17:28
@MikeOttink is part of the algorithms library, but is not part of the header. — jaggedSpire, Jan 10 '17 at 20:19

score 3 · Accepted Answer · answered Jan 10 '17 at 16:47

The algorithm to preform this operation is in the numeric header, not in the algorithm header. See std::accumulate.

#include <iostream>
#include <numeric>
#include <vector>

int main()
{
    std::vector<int> data = {1, 2, 10};
    const auto result = std::accumulate(data.begin(), data.end(), 0);
    std::cout << result << std::endl;
    return 0;
}

If you insist on using functional and algorithm you could use std::for_each and std::function.

#include <algorithm>
#include <iostream>
#include <functional>
#include <vector>

int main()
{
    std::vector<int> data = {1, 2, 10};
    int result = 0;

    std::function<void(int)> sum = [&result](int value){result += value;};
    std::for_each(data.begin(), data.end(), sum);

    std::cout << result << std::endl;
    return 0;
}

Is it possible to add all of a vector's numbers using and ?

1 Answers1