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# Need help with a factorial program

Member Posts: 1
I'm just starting and i need help with this problem:

Write a recursive function Factorial() that returns the factorial (a long) of its int argument. The factorial of a positive integer is the product of it and all the positive integers less than it. For example, the factorial of 5 is 5*4*3*2*1 or 120. The symbol for factorial is the exclamation point, therefore 5!=120. Computing this factorial can also be thought of as 5!=4! or more generally, N!=N*(N-1)! By definition, 0! is equal to 1.

Any help would be great. Thanks.

• Member Posts: 127
Hi,

Something like this:

[code]
#include

long factorial(long a)
{
if (a > 1)
return (a * factorial(a-1));
else
return (1);
}

int main()
{
// Declaring the variables
long l;
std::cout << " Please enter a positive number: ";
std::cin >> l;

std::cout << l << "! = " << factorial(l) << std::endl;

return 0;
}
[/code]

• Member Posts: 38
Hey buddy well i'll give you something to start on ok

long Factorial( long& n)
{
// test if n is 0 , then you have to return 1 right?

else
return n times myself(n-1) // recursive call here
}

not exactly the most efficient way to do it but it's probably what your
learning now.

hope it helps,
Mel

• USAMember Posts: 0

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• Member Posts: 2

# include <conio.h>

main ()
{
long i, n, faktor;
printf ("Enter the number to be factoried: ");
scanf ("%ld", &n);
faktor=1;
for (i=1; i<=n; i++)
{
faktor = i; /n! = 1x2x3x....xn */
}
printf ("%ld! = %ld\n", n, faktor);

}

• Member Posts: 2

doesn't work