Recursion on Arrays and Strings in DSA C - Build from Scratch

Sum of Array Elements Using Recursion

📖 Scenario: Imagine you have a list of daily expenses saved in an array. You want to find the total amount spent using a simple program.

🎯 Goal: Build a C program that uses recursion to calculate the sum of all elements in an integer array.

📋 What You'll Learn

Create an integer array with exact values

Create a variable for the array size

Write a recursive function to sum the array elements

Print the final sum

💡 Why This Matters

🌍 Real World

Recursion helps solve problems like summing expenses, searching, or processing data step-by-step in many software applications.

💼 Career

Understanding recursion is important for software developers to write clean and efficient code for tasks like data processing, algorithms, and problem-solving.

1

Create the array of expenses

Create an integer array called expenses with these exact values: 100, 200, 300, 400, 500.

DSA C

# Your code here

Hint

Use curly braces to list the values inside the array.

2

Set the size of the array

Create an integer variable called size and set it to the number of elements in the expenses array, which is 5.

DSA C

int expenses[] = {100, 200, 300, 400, 500};
# Your code here

Hint

Count the number of elements in the array and assign it to size.

3

Write the recursive function to sum the array

Write a recursive function called sumArray that takes two parameters: an integer array arr and an integer n representing the size. The function should return the sum of the first n elements. Use the base case when n is 0 to return 0. Otherwise, return the last element plus the sum of the rest.

DSA C

int expenses[] = {100, 200, 300, 400, 500};
int size = 5;

// Your code here

Hint

Use the last element arr[n - 1] and call sumArray with n - 1.

4

Print the sum of the array

Call the sumArray function with expenses and size, store the result in an integer variable called total, and print total using printf.

DSA C

int expenses[] = {100, 200, 300, 400, 500};
int size = 5;

int sumArray(int arr[], int n) {
    if (n == 0) {
        return 0;
    } else {
        return arr[n - 1] + sumArray(arr, n - 1);
    }
}

// Your code here

Hint

Use printf("%d\n", total); to print the sum.