Find Factorial of Number without using function
#include<stdio.h>
#include<conio.h>
void main()
{
int i,number,factorial;
printf("nEnter the number : ");
scanf("%d",&n);
factorial = 1;
for(i=1;i<=n;i++)
factorial = factorial * i;
printf("nFactorial of %d is %d",n,factorial );
getch();
}
Output :
Enter the number : 5
Factorial of 5 is 120
Explanation of Program :
Before Explaining the program let us see how factorial is calculated -
Factorial of 5 = 5!
= 5 * 4!
= 5 * 4 * 3!
= 5 * 4 * 3 * 2!
= 5 * 4 * 3 * 2 * 1!
= 5 * 4 * 3 * 2 * 1 * 0!
= 5 * 4 * 3 * 2 * 1 * 1
= 120
Firstly accept the number whose factorial is to be found.
printf("nEnter the number : ");
scanf("%d",&n);
We have to iterate from 1 to (n-1) using for/while/do-while loop. In
each iteration we are going to multiply the current iteration number and
result.
for(i=1;i<=n;i++)
factorial = factorial * i;
Some Precautions to be taken :
Precaution 1 : Initialize ‘factorial’ variable
factorial = 1;
before going inside loop we must initialize factorial variable to 1
since by default each c variable have garbage value. If we forgot to
initialize variable then garbage value will be multiplied and you will
get garbage value as output.
Precaution 2 : For loop must start with 1
Suppose by mistake we write following statement -
for(i=0;i<=n;i++)
factorial = factorial * i;
then in the very first iteration we will get factorial = 0 and in all
successive iteration we will get result as 0 since anything multiplied
by Zero is Zero
Precaution 3 : Try to accept lower value to calculate factorial
We have 2 bytes to store the integer in Borland C++ compiler, so we
can have maximum limit upto certain thousand. Whenever we try to accept
value greater than 20 we will get factorial overflow.
