C program to find sum of array elements

Write a C program to read elements in an array and find the sum of array elements. C program to find sum of elements of the array. How to add elements of an array using for loop in C programming. Logic to find sum of array elements in C programming.

Input elements: 10, 20, 30, 40, 50

Sum of all elements = 150

Required knowledge

Basic Input Output, For loop, Array

Logic to find sum of array elements

Finding sum of array elements is easy when you know how to iterate through array elements. In this post I will explain two approaches to find sum of array elements. First let us begin with the easiest approach.

1. Input size and elements in array, store in some variable say n and arr[n].
2. To store sum of array elements, initialize a variable sum = 0. Note: sum must be initialized only with 0.
3. To find sum of all elements, iterate through each element and add the current element to the sum. Which is run a loop from 0 to n. The loop structure should look like for(i=0; i<n; i++).
4. Inside the loop add the current array element to sum i.e. sum = sum + arr[i] or even you can do sum += arr[i].

Program to find sum of array elements

/**
 * C program to find sum of all elements of array 
 */

#include <stdio.h>
#define MAX_SIZE 100

int main()
{
    int arr[MAX_SIZE];
    int i, n, sum=0;

    /* Input size of the array */
    printf("Enter size of the array: ");
    scanf("%d", &n);

    /* Input elements in array */
    printf("Enter %d elements in the array: ", n);
    for(i=0; i<n; i++)
    {
        scanf("%d", &arr[i]);
    }

    /*
     * Add each array element to sum
     */
    for(i=0; i<n; i++)
    {
        sum = sum + arr[i];
    }


    printf("Sum of all elements of array = %d", sum);

    return 0;
}

Note: You can also re-write this program using a shorter and efficient approach using single for loop as written below.

Read more – Program to find sum of array elements using recursion

Program to find sum of array elements – best approach

/**
 * C program to find sum of all elements of array
 */

#include <stdio.h>
#define MAX_SIZE 100

int main()
{
    int arr[MAX_SIZE];
    int i, n, sum=0;

    /* Input size of the array */
    printf("Enter size of the array: ");
    scanf("%d", &n);

    /* Input elements in array */
    printf("Enter %d elements in the array: ", n);
    for(i=0; i<n; i++)
    {
        scanf("%d", &arr[i]);

        // Add each array element to sum
        sum += arr[i];
    }

    printf("Sum of all elements of array = %d", sum);

    return 0;
}

Enter size of the array: 10
Enter 10 elements in the array : 10 20 30 40 50 60 70 80 90 100
Sum of all elements of array = 550

Note: I have used shorthand assignment operator in sum += arr[i] which is equivalent to sum = sum + arr[i]. You could use any of them.

Learn more about shorthand operators in C programming.

Happy coding 😉