To Find Factorial of a Number
Factorial of a Number
For any positive number n, its factorial is given by:
factorial = 1*2*3*4....n
If a number is negative, factorial does not exist and factorial of 0 is 1.This program takes an integer from a user. If user enters negative integer, this program will display error message and if user enters non-negative integer, this program will display the factorial of that number.
Source Code
/* C program to display factorial of an integer if user enters non-negative integer. */
#include <stdio.h>
int main()
{
int n, count;
unsigned long long int factorial=1; /* you can only write int */
printf("\nEnter an integer: \n");
scanf("%d",&n);
if ( n< 0)
printf("\nError!!! Factorial of negative number doesn't exist.\n");
else
{
for(count=1;count<=n;++count) /* for loop terminates if count>n */
{
factorial= factorial * count; /* factorial=factorial*count */
}
printf("\nFactorial = %lu\n",factorial); /* lu is for unsigned long long int */
}
return 0;
}
Output 1
Enter an integer: -5
Error!!! Factorial of negative number doesn't exist.
Output 2
Enter an integer: 10
Factorial = 3628800
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