Factorial Program In C Using While Loop With Example

 Factorial Program in C Using While Loop

/* C PROGRAM FOR FACTORIAL USING WHILE LOOP - FACTORIAL.C */

#include<stdio.h>
#include<conio.h>

void main() //main method

{
   //variable declaration
   long int calcfact =1;
   int i=1,n;

   clrscr();

   printf("Enter a a positive number : "); //asking user to enter a num
   scanf("%d",&n); //reading entered number by user

   while(i<=n) //while loop logic for factorial

   {

     calcfact*=i; //calcfact = calcfact*i;

     i++;

   }

printf("factorial of %d is = %ld  \n", n, calcfact); 

   getch();

}

FACTORIAL PROGRAM IN C USING While Loop OUTPUT

After you compile and run the above factorial program in c to find the factorial of a number using while loop, your C compiler asks you to enter a number to find factorial. After you enter your number, the program will be executed and give output like below expected output.

Output – 1

Enter a positive number: 6
Factorial of 6 is = 720

FACTORIAL Program in C using Recursion with Explanation

• The program execution starts from main() function.
• Define three variable n, i, calcfact.
• Asks the user to enter a positive number to find factorial using printf().
• Gets the value from the user using scanf() function.
• Let’s take a variable ‘i’ with an initial value of 1 to compare with user entered value ‘n’.
• Now while loop will be executed until the statement while(i<=n) is false.
• In each iteration in while loop, ‘i’ value will be increased (i++) and checked with ‘n’ (i<=n).
• The ‘i’ value is multiplied with ‘calcfact’ variable and the new value will be stored in ‘calcfact’ variable. calcfact*=i; or calcfact = calcfact*i;
• When while statement gets false, the compiler gets out of the while loop and prints the factorial of the entered number.
• 1*2*3*4*5*6 = 720

C PROGRAMMING EXAMPLES