simplify recursive function

This is a discussion on simplify recursive function within the C++ Programming forums, part of the General Programming Boards category; I am attempting the challenge at the end of the recursion tutorial on this site to return the factorial of ...

  1. #1
    Registered User
    Join Date
    Dec 2010
    Posts
    48

    simplify recursive function

    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.

  2. #2
    -bleh-
    Join Date
    Aug 2010
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    Quote Originally Posted by MattJ812 View Post
    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);
    }
    "All that we see or seem
    Is but a dream within a dream." - Poe

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