C program for sum of the digits in a given number - My CS Tutorial

How to write a program that find the sum of all digits in a number?

         In this tutorial we will learn how to write a program that find and display the sum of all digits in a number.

Explanation:-

Here we did initialization for

dum----->To store the entered value(i.e 'n') as you will come to know at the end of the program.

n----------->To store number given by user.

sum----->To store the sum of all digits in the number.It is initialized to zero.

x---------->To store n%10.

First of all we got a number 'n' from user and then stored it in a dummy variable called as 'dum' for restoring the value.(remember this point).

Now the main logic comes here:-

let the number 'n' be 321 and as 321>0,while loop gets executed

then x=321%10--->which is 1.

sum=0+1-------->1

n=321/10--------->32

The sum for the first loop execution is sum=1.

Now the number 'n' has become '32' and n>0,while loop executes for 2nd time

then x=32%10--->which is 2.

sum=1+2-------->3

n=32/10--------->3

The sum when loop executed second time is sum=3.

Now the number 'n' has become '3' and n>0,while loop executes for 3rd time

then x=3%10--->which is 3.

sum=3+3-------->6

n=3/10--------->0

The sum when loop executed third time is sum=6.

Now as the number in variable 'n' is 0 which is not n>0 then the loop terminates.Then the final sum is '6'.

So now I hope you understood why the dummy variable is used.It is because the value in 'n' becomes 0 at the end of the program so for restoring this value to print at the end we used 'dum'(as from the 2nd point).

Finally it prints the value in 'sum'.

C program code

#include<stdio.h>

#include<conio.h>

void main()

{

 int dum,n,sum=0,x;

 printf("\n Enter a number:\n ");

 scanf("%d",&n);

 dum=n;

 while(n>0)

 {

   x=n%10;

   sum=sum+x;

   n=n/10;

 }

 printf("\n The sum of all digits in %d is %d\n",dum,sum);

 getch();

}

OUTPUT 1:

OUTPUT 2:

In first output,the input value is 7869

The sum of all digits in this number is 30

7 + 8 + 6 + 9 = 30

As the same in second output, the input value is 5562

The sum of all digits in this number is 18

5 + 5 + 6 + 2 = 18

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Created by-- HARSH CHAUHAN