finding factorial of large integer like 100 is easy in python as it has inbuilt support for such large integer but c is not fortunate enough. This C code tries to give such power to the user. You can easily find factorial of very large number. I have successfully calculated factorial of an integer as large as 15000.

factorial

/*     This program is for finding the factorial of a number.
	Author: Shashi Kant
*/

#include<stdio.h>
int main()
{	
	int a[1000000];
	long long unsigned int num,f,z,temp;
	scanf("%lld",&num);
	int i,j;
	f=num;
	for (i=0;num>0;i++,num /=10)
		a[i]=num%10;
	while((--f)>1)
	{	
		temp = 0; z=0;
		for (j=0;j<i;j++)
		{
			z = f * a[j] + temp;
			a[j] = z%10;
			temp = z/10;
		}
		while(temp)
		{
			a[j++] = temp%10;
			temp /=10;
		}
		i=j;
	}
	for(--i;i>=0;i--)
		printf("%d",a[i]);
	printf("\n");
	return 0;

}