Thread: simplify recursive function

Originally Posted by MattJ812

I am attempting the challenge at the end of the recursion tutorial on this site to return the factorial of any number.

I have come up with 2 ways to do it, but both seem a bit cumbersome.

Code:

#include <iostream>

using namespace std;

void Recurse(int number,int factorial)
{
    if (number == 1)
    {
        cout << "The factorial of your number is: " << factorial << ".\n";
        return;
    }

    Recurse(number-1,factorial*(number-1));
}

int main()
{
    int number;
    cout << "Please enter a positive number:";
    cin >> number;

    if (number < 0)
        cout << "You entered a Negative Number!\nExiting...\n";
    else
    if (number == 0)
        cout << "The Factorial of your number is 1.\n";
    else
        Recurse(number,number);

    return 0;
}

Code:

#include <iostream>

using namespace std;

// number is the number entered by the user.
// count is going to increment by 1, starting at 1.
// factorial is going to hold the product of all numbers from 1 to number.
void Recurse(int number, int count, int factorial)
{
    if (number < 0) // return if the input was negative.
    {
        cout << "You Entered a Negative Number.\n";
        return;
    }
    if ((count-1) == number) // This check includes 0 as to return a factorial of 1.
    {
        cout << "The factorial of your number is: " << factorial << ".\n";
        return;
    }

    Recurse(number,count+1,factorial*count);
}

int main()
{
    int number;
    cout << "Please enter a positive number:";
    cin >> number;

    Recurse(number,1,1);

    return 0;
}

I feel that there is too much code for something so simple, how could I rewrite these to simplify things a little?

Thanks.

you can let your recursion function return an int. something like this would do.

Code:

int recurse( int number)
{
  if( number == 1)
    return 1;
  else
    return number*recurse(number-1);
}