Programs to calculate the sum of the elements in an array have been shown here. The following section also covers the algorithm, pseudocode and time complexity of the program.

## 1. Algorithm to calculate the sum of the elements in an array

1. Take input of an array A[] and the size n

2. Set i = 0 and sum = 0

3. Perform sum = sum + A[i]

4. Perform i = i + 1.

5. If i < n, go to step 3 else display sum as the result.

## 2. Pseudocode to calculate the sum of the elements in an array

Input: An array $A[~]$ and size of array $n$

Output: Sum of the elements in $A[~]$

1. Procedure arraySum($A[~]$, $n$):

2. $sum \leftarrow 0$

3. Repeat for $i \in [0, n - 1]$:

4. $sum = sum + A[i]$:

5. Return $sum$

6. End Procedure

## 3. Time complexity to calculate the sum of the elements in an array

Time Complexity: O(n)

Where n is the total no of elements in the array.

## 4. C Program & output to calculate the sum of the elements in an array using iteration

Code has been copied
/*******************************
alphabetacoder.com
C program to calculate the sum
of the elements using iteration
*********************************/

#include <stdio.h>

int main() {
// declare an array
int arr = {10, 20, 30, 40, 50};
// declare variables
int i, sum;

// initialize variable
sum = 0;

// add an element to sum in each iteration
for (i = 0; i < 5; i++) {
sum = sum + arr[i];
}

// display result
printf("Total sum = %d", sum);

return 0;
}


Output

Total sum = 150

## 5. C Program & output to calculate the sum of the elements in an array using recursion

Code has been copied
/*******************************
alphabetacoder.com
C program to calculate the sum
of the elements using recursion
*********************************/

#include <stdio.h>

// recursive function to find
// sum of elements in array
int find_sum(int arr[], int sum, int i){
// exit condition
if(i < 0)
return sum;
// add current element to sum
sum = sum + arr[i];
// call function
return find_sum(arr, sum, i - 1);
}

int main(){
// declare an array
int arr = {15, 25, 35, 45, 55};
// declare variables
int min, length, sum;

// calculate size of array
length = sizeof(arr)/sizeof(arr);

// initialize variable
sum = 0;

// call function to get the
// sum of elements as return value
// pass the array, sum = 0 and the
// size of the array
sum = find_sum(arr, 0, length - 1);

// display result
printf("Total sum = %d", sum);

return 0;
}


Output

Total sum = 150