`lucproblem014.c`¶

Problem Statement

Write a function that receives integers and returns the sum, average and standard deviation of these numbers. Call this function from main() and print the result in main()

Metadata¶

Property	Detail
Author	Amit Dutta amitdutta4255@gmail.com
Date	12 Dec 2025
License	MIT License (See the LICENSE file for details)
Difficulty	Beginner (index: 3 / 10)

Concepts¶

Beta Feature

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Pointers
Recursion
Sorting (possible)
Iteration

Actions¶

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Source Code¶

#include <stdio.h>
#include <math.h>

// Function prototype: Using pointers for 'call by reference' to return 3 values.
void stats(double *, double *, double *);

int main()
{
    double sum, average, standardDeviation;
    // Passing addresses of variables to receive results from the function.
    stats(&sum, &average, &standardDeviation);

    printf("\n--- Stats ---"
           "\nSum: %g"
           "\nAverage: %g"
           "\nStandard Deviation: %g",
           sum, average, standardDeviation);
    return 0;
}

// Function to calculate statistics on user-provided numbers.
void stats(double *sum, double *average, double *standardDeviation)
{
    int n;
    // Input Validation Loop for N
    do
    {
        printf("How many numbers you want to give input: ");

        if (scanf("%d", &n) == 1)
        {
            break;
        }
        else
        {
            printf("\nPlease enter a valid number.\n");
            // Clearing input buffer to handle invalid input
            while (getchar() != '\n' && !feof(stdin))
                ;
        }
    } while (1);

    // Variable-Length Array (VLA) to store the input numbers.
    double inputNumber[n];
    int i = 0;

    printf("\n--- Enter Numbers ---\n");

    // Input Loop for numbers
    while (i < n)
    {
        printf("Enter number %d: ", i + 1);

        if (scanf("%lf", &inputNumber[i]) == 1)
        {
            // Clearing input buffer after successful read
            while (getchar() != '\n')
                ;
            i++;
        }
        else
        {
            printf("Invalid input. Only integers are allowed. Please try again.\n");
            // Clearing input buffer to handle invalid input
            while (getchar() != '\n' && !feof(stdin))
                ;
        }
    }

    // 1. Sum Calculation
    double tempSum = 0;
    for (i = 0; i < n; i++)
        tempSum += inputNumber[i];

    // 2. Average (Mean) calculation
    double tempAverage = tempSum / n;

    // 3. Standard Deviation (Sample SD formula used)
    double tempStandardDeviation = 0.0;

    // Preventing division by zero if n is 1. SD is 0 for a single number.
    if (n > 1)
    {
        double tempSumation = 0;
        // calculating the sum of squared differences from the mean
        for (i = 0; i < n; i++)
            tempSumation += pow((inputNumber[i] - tempAverage), 2.0);

        // Calculating sample standard deviation
        tempStandardDeviation = sqrt(tempSumation / (n - 1));
    }

    // Assigning final values back to the variables in main().
    *sum = tempSum;
    *average = tempAverage;
    *standardDeviation = tempStandardDeviation;
}

Explanation¶

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    You are explaining a C programming code to a beginner.

    STRICT RULES:

    - Only use the given code. Do NOT assume anything not present.

    - Do NOT add extra examples.

    - Keep explanation clear and short.

    - If something is unclear, say "Not clear from code".

    - Follow the exact format below. Do NOT change headings.

    FORMAT:

    [START]

    ## What it does

    (Explain the overall purpose in 1-2 sentences)

    ## Step-by-step

    (Explain how the code works in steps, simple language)

    ## Key Concepts

    (List concepts like loop, condition, function, etc.)

    ## Notes

    (Mention any limitations, errors, or assumptions)

    [END]

    CODE (lucproblem014.c):

    #include <stdio.h>
    #include <math.h>

    // Function prototype: Using pointers for 'call by reference' to return 3 values.
    void stats(double *, double *, double *);

    int main()
    {
        double sum, average, standardDeviation;
        // Passing addresses of variables to receive results from the function.
        stats(&sum, &average, &standardDeviation);

        printf("\n--- Stats ---"
               "\nSum: %g"
               "\nAverage: %g"
               "\nStandard Deviation: %g",
               sum, average, standardDeviation);
        return 0;
    }

    // Function to calculate statistics on user-provided numbers.
    void stats(double *sum, double *average, double *standardDeviation)
    {
        int n;
        // Input Validation Loop for N
        do
        {
            printf("How many numbers you want to give input: ");

            if (scanf("%d", &n) == 1)
            {
                break;
            }
            else
            {
                printf("\nPlease enter a valid number.\n");
                // Clearing input buffer to handle invalid input
                while (getchar() != '\n' && !feof(stdin))
                    ;
            }
        } while (1);

        // Variable-Length Array (VLA) to store the input numbers.
        double inputNumber[n];
        int i = 0;

        printf("\n--- Enter Numbers ---\n");

        // Input Loop for numbers
        while (i < n)
        {
            printf("Enter number %d: ", i + 1);

            if (scanf("%lf", &inputNumber[i]) == 1)
            {
                // Clearing input buffer after successful read
                while (getchar() != '\n')
                    ;
                i++;
            }
            else
            {
                printf("Invalid input. Only integers are allowed. Please try again.\n");
                // Clearing input buffer to handle invalid input
                while (getchar() != '\n' && !feof(stdin))
                    ;
            }
        }

        /
    ... (truncated for brevity)

lucproblem014.c¶