In this Answer, we will go over how to sum up all the values in a one-dimensional array.


There are two main ways to achieve this, as discussed below.

# 1. Use a `for` loop
We can use a `for` loop to traverse the array. All the elements can be added up one by one:

1. Initialize `sum = 0`. 
2. Run a `for` loop from `i = 0` to `i = size - 1`.
3. At every iteration of the `for` loop, add `sum` and the current element of the array, i.e., `sum = sum + arr[i]`.
4. At the end of the `for` loop, the sum of all the elements will be stored in the `sum` variable.

#include <iostream>
using namespace std;

int main() {
  // initialise array
  int arr[] = {2, 4, 6, 8};
  int size = 4;

  // initialise sum to zero
  int sum = 0;

  // for loop runs from 0 to size - 1
  for(int i = 0; i < size; i++)
  {
    sum = sum + arr[i];
  }

  cout << "The sum of the elements in the array: " << sum;
}

# 2. Use the `accumulate()` function
The *`accumulate()` function* is defined in the `<numeric>` header file, which must be included at the start of the code in order to access this function:
```
accumulate(arr , arr+size , sum);
``` 
The function takes three arguments:
1. **`arr`**: The name of the array.
2. **`arr+size`**: The name of the array + size of the array.
3. **`sum`**: The variable in which the sum needs to be stored.

The function returns an `int` value, which is the sum of all the elements in the array.

#include <iostream>
#include<numeric>
using namespace std;

int main() {
  // initialise array
  int arr[] = {2, 4, 6, 8};
  int size = 4;

  // initialise sum to zero
  int sum = 0;

  // use function
  sum = accumulate(arr, arr+size, sum);

  cout << "The sum of the elements in the array: " << sum;
}

How to find the sum of values in an array in C++

Use a for loop or the accumulate function to sum values in a one-dimensional C++ array.

How to find the sum of values in an array in C++

1. Use a for loop

Dry run of for loop

2. Use the accumulate() function

1. Use a `for` loop

Dry run of `for` loop

2. Use the `accumulate()` function