Summation Using Iteration Loop

Make a program that continuously prompts the user to enter integer numbers. The program should accept and store these numbers in a std::vector<int>. If the user enters a negative number, the program should stop asking for more numbers.

Use an iteration loop to output all of the stored numberes, and calculate the sum of them. Then output the sum.

Answer

#include <iostream>
#include <vector>

int main() {
    std::vector<int> numbers;
    int input;

    // Prompt for input until a negative number is entered
    std::cout << "Enter numbers (negative number to end): ";
    while (std::cin >> input && input >= 0) {
        numbers.push_back(input);
    }

    int sum = 0;
    std::cout << "Elements in the vector: ";
    // Iterate over the vector, print each element, and add to sum
    for (int num : numbers) {
        std::cout << num << " ";
        sum += num;
    }

    // Output the sum
    std::cout << "\nSum of elements: " << sum << std::endl;

    return 0;
}

In this program std::cin >> input is included as part of the while condition. std::cin >> input will be evaluated as false if there is a type missmatch, or an input failure. This effectively makes it so that the input will stop if the user inputs a value that doesn't work with our program. This goes beyond the original scope of the task. Putting std::cin >> input inside the while loop and checking that it's positive before calling push_back is also sufficient.