在不使用迭代器的情况下，将向量中的整数相加，第一个和第二个元素的和为to，依此类推

Question

#include <iostream>
#include <vector>

using namespace std;

int main() 
{
    int typedNos;
    if (cin >> typedNos) 
    {
        vector <int> inputNos{ typedNos }; 

        while (cin >> typedNos)
        {
            inputNos.push_back(typedNos); 
        }


        for (decltype (inputNos.size()) n = 1; n < inputNos.size(); ++n)
        {

            cout << inputNos[0] + inputNos[1] << '\t' << inputNos[(2 * n) - 1]
                   + inputNos[(2 * n)] << endl;

            return 0;
        }
    }
    else
    {
        cerr << " Wrong input type or no input was typed!" << endl;
        //return -1;
    }
}

Everything works fine till the output statement in the for loop is reached. The first two pairs of the vector's elements are manually added to account for zero. The rest are to be added automatically. But this only works for the first pair.

So, for example, an input of:

1 2 3 4 5.

Will give you an output of:

3 5.

Instead of 3 5 7 9.

This is where I have an issue. I have seen other methods of solving this problem but my question is why the sequence 2n (even positions) and 2n-1 (odd positions) do not work for the entire vector? Remember this question does not allow me to use iterators. Thanks.

Answer 1

The problem lies in your for-loop . Using return inside a loop will still exit from the current function. Your current function is main , so this ends the program.

I'm not really sure why you think you need 2 * n . It seems you want to iterate over every object, not every second one.

for (std::size_t n = 1; n < inputNos.size(); ++n) {
    std::cout << inputNos[n] + inputNos[n-1] << '\t';
}
std::cout << std::endl;