TCS Coding Practice Question | Sum of Digits of a number

Given a number, the task is to find the Sum of Digits of this number using Command Line Arguments. Examples:

Input: num = 687
Output: 21

Input: num = 12
Output: 3

Approach:

• Since the number is entered as Command line Argument, there is no need for a dedicated input line
• Extract the input number from the command line argument
• This extracted number will be in string type.
• Convert this number into integer type and store it in a variable, say num
• Declare a variable to store the sum and set it to 0
• Repeat the next two steps till the number is not 0
• Get the rightmost digit of the number with help of remainder ‘%’ operator by dividing it with 10 and add it to sum.
• Divide the number by 10 with help of ‘/’ operator
• Print or return the sum

Program:

C

// C program to find
// the sum of digits of a number
// using command line arguments

#include <stdio.h>
#include <stdlib.h> /* atoi */

// Function to Find the sum of digits
int findSumOfDigits(int num)
{

    // Variable to store the
    // the sum of digits
    int sum = 0;

    // Traverse through the number digit by digit
    while (num > 0) {

        // Add the last digit of num
        // to the sum
        sum = sum + (num % 10);

        // Remove the last digit from the num
        num = num / 10;
    }

    // Return the sum
    return sum;
}

// Driver code
int main(int argc, char* argv[])
{

    int num;

    // Check if the length of args array is 1
    if (argc == 1)
        printf("No command line arguments found.\n");
    else {

        // Get the command line argument and
        // Convert it from string type to integer type
        // using function "atoi( argument)"
        num = atoi(argv[1]);

        // Find the sum of digits and print it
        printf("%d\n", findSumOfDigits(num));
    }
    return 0;
}

Java

// Java program to find
// the sum of digits of a number
// using command line arguments

class GFG {

    // Function to Find the sum of digits
    public static int findSumOfDigits(int num)
    {

        // Variable to store the
        // the sum of digits
        int sum = 0;

        // Traverse through the number digit by digit
        while (num > 0) {

            // Add the last digit of num
            // to the sum
            sum = sum + (num % 10);

            // Remove the last digit from the num
            num = num / 10;
        }

        // Return the sum
        return sum;
    }

    // Driver code
    public static void main(String[] args)
    {

        // Check if length of args array is
        // greater than 0
        if (args.length > 0) {

            // Get the command line argument and
            // Convert it from string type to integer type
            int n = Integer.parseInt(args[0]);

            // Find the sum of digits and print it
            System.out.println(findSumOfDigits(n));
        }
        else
            System.out.println("No command line "
                               + "arguments found.");
    }
}

Output:

• In C:
• In Java:

Time complexity: O(logn)

Auxiliary Space: O(1)