Sum of All Digits in a Number

This code takes a positive integer input, extracts each digit, calculates the sum of these digits, and then displays the original number and the sum. The program utilizes a while loop to achieve this task.

#include<stdio.h>
main()
{
 int dummy,n,sum=0,x;
 printf("Enter a number\n");
 scanf("%d",&n);
 dummy=n;
 while(n>0)
 {
   x=n%10;
   sum=sum+x;
   n=n/10;
 }
 printf("The sum of all digits in %d is %d\n",dummy,sum);
}

Enter a number
12
The sum of all digits in 12 is 3

Explanation:

This C program calculates the sum of all the digits in a positive integer entered by the user. Here’s a step-by-step explanation of the code:

Header File:

The program includes the standard C library header <stdio.h> for input and output operations.

Main Function:

The main function is the entry point of the program.

Variable Declaration:

Four variables are declared:

• n (int): It is used to store the user input, which is the number for which the digit sum is to be calculated.
• dummy (int): This variable stores a copy of n for later printing the result.
• sum (int): This variable is used to accumulate the sum of digits.
• x (int): It temporarily stores each digit extracted from n.

User Input:

The program prompts the user to enter a number:

• “Enter a number” for n.

The user’s input is read and stored in the variable n using scanf.

Initialization:

dummy is set to the same value as n. This step is done to keep a copy of the original number, as n will be modified in the subsequent calculations.

While Loop:

• The code uses a while loop to extract and sum the individual digits of the number n.
• The loop continues as long as n is greater than 0.

Digit Extraction:

• Within the loop, x is used to store the rightmost digit of n. This is done by calculating n % 10, which gives the remainder when n is divided by 10. This remainder is the rightmost digit.

Sum Calculation:

• The value of x (the rightmost digit) is added to the sum. This step accumulates the sum of the digits.

Digit Removal:

• The rightmost digit is removed from n by dividing it by 10 (n = n / 10). This operation effectively removes the rightmost digit, and the process continues with the remaining digits.

Print Result:

• After the loop completes, the program uses printf() to display the original number and the sum of its digits. The format specifier %d is used to print integer values.

End of Program:

• Once the result is displayed, the program reaches the end of the main function and terminates.