write Factorial of a Number in C using do-while Loop program

Factorial program by using do while loop

Program 

#include<stdio.h>

#include<conio.h>

void main()

{

    int n,i=1,f=1;

    clrscr();

     

    printf("\n Enter The Number:");

    scanf("%d",&n);

     

    //LOOP TO CALCULATE THE FACTORIAL OF A NUMBER

    do

    {

        f=f*i;

        i++;

    }while(i<=n);

     

    printf("\n The Factorial of %d is %d",n,f);

    getch();

}

Working:

1. First the computer reads the number 
2. To find the factorial of the number from the user.
3. Using do-while loop the value of ‘i’ is multiplied with the value of ‘f’. 
4. The loop continues till the value of ‘i’ is less than or equal to ‘n’(i<=n).
5. Finally the factorial value of the given number is printed.

Step by Step working of the above Program Code:

Let us assume that the number entered by the user is 6.

1. It assign the value of n=6 , i=1 , f=1.
2. Then the loop continues till the condition of the do-while loop is true.

• do

• f=f*i (f=1*1) So f=1

• i++ (i=i+1) So i=2

• i<=n (2<=5) , do-while loop condition is true.

•  do

• f=f*i (f=1*2) So f=2

• i++ (i=i+1) So i=3

• i<=n (3<=5) , do-while loop condition is true.

• do

• f=f*i (f=2*3) So f=6

• i++ (i=i+1) So i=4

• i<=n (4<=5) , do-while loop condition is true.

• do

• f=f*i (f=6*4) So f=24

• i++ (i=i+1) So i=5

• i<=n (5<=5) , do-while loop condition is true.

• do

• f=f*i (f=24*5) So f=120

• i++ (i=i+1) So i=6

i<=n (5<=6) , do-while loop condition is true.

do

f=f*i (f=120*6) So f=720

i++ (i=i+1) So i=7

i<=n (7<=6) , do-while loop condition is false.

 It comes out of the do-while loop.

Finally it prints as given below

The Factorial of 6 is 720

Thus the program execution is completed.

Dall