C++ Program For Average of an Array (Iterative and Recursive)

The average of an array is calculated by dividing the sum of all its elements by the total number of elements.

• It can be calculated using iterative or recursive approaches.
• The result should generally be stored in a floating-point type to handle non-integer averages.

Examples:

Input: arr[] = {1, 2, 3, 4, 5}
Output: 3

Explanation: The sum is 15 and the number of elements is 5, so the average is 15 / 5 = 3.

Input: arr[] = {10, 20, 30, 40}
Output: 25

Explanation: The sum is 100 and the number of elements is 4, so the average is 100 / 4 = 25.

Iterative Approach

The iterative approach traverses the array, calculates the sum of its elements, and divides the sum by the array size.

Steps:

1. Initialize a variable to store the sum.
2. Traverse the array and add each element to the sum.
3. Divide the sum by the number of elements.
4. Return the resulting average.

#include <iostream>
using namespace std;

// Function to find average of an array
double average(int arr[], int n)
{
    if (n == 0)
        return 0;

    long long sum = 0;

    for (int i = 0; i < n; i++)
        sum += arr[i];

    return static_cast<double>(sum) / n;
}

int main()
{
    int arr[] = {10, 2, 3, 4, 5, 6, 7, 8, 9};
    int n = sizeof(arr) / sizeof(arr[0]);

    cout << average(arr, n) << endl;

    return 0;
} 

6

Explanation

• The average() function traverses all elements and calculates their sum.
• The sum is divided by n, the number of elements.
• static_cast<double> ensures that the division produces a floating-point result when required.

Recursive Approach

The recursive approach calculates the sum of the array elements recursively and divides the final sum by the number of elements.

Steps:

1. Start from the first element of the array.
2. Recursively calculate the sum of the remaining elements.
3. Add the current element to the returned sum.
4. Divide the total sum by the number of elements.

#include <iostream>
using namespace std;

// Recursively calculates the sum
long long sumRec(int arr[], int i, int n)
{
    if (i == n)
        return 0;

    return arr[i] + sumRec(arr, i + 1, n);
}

// Function to find average of an array
double average(int arr[], int n)
{
    if (n == 0)
        return 0;

    return static_cast<double>(sumRec(arr, 0, n)) / n;
}

int main()
{
    int arr[] = {10, 2, 3, 4, 5, 6, 7, 8, 9};
    int n = sizeof(arr) / sizeof(arr[0]);

    cout << average(arr, n) << endl;

    return 0;
} 

6

Explanation

• sumRec() recursively visits each array element and adds it to the sum.
• The recursion stops when i reaches n.
• The total sum is then divided by the number of elements to obtain the average.