Thread: Recursion

  1. #1
    Registered User
    Join Date
    Jul 2010


    Hey. I'm trying to learn C++... not very good at it though, at all. =/

    I'm on lesson 16 and I REALLY just can't seem to get the solution to the challenge they've set... Tutorial: Recursion
    This is just the beginning of the usefulness of recursion. Heres a little challenge, use recursion to write a program that returns the factorial of any number greater than 0. (Factorial is number*number-1*number-2...*1).
    I really have tried and tried to work it out. But as I said, I'm not good at all, but I really am interested in this sort of stuff & computers.

    Any help please? Thanks.

  2. #2
    Registered User MacNilly's Avatar
    Join Date
    Oct 2005
    CA, USA
    Factorial is:

    !x = 1 if x = 0, else it is x * !(x - 1)

    Any recursive function has to have a "base case" where the recursion stops. For factorial the base case is x=0.

    So you want to write a function fact() that has x as the argument.

    If x = 0, you can just return 1.

    If it is not 0, though, you need to return x * !(x - 1). If only you had a function to computer !(x-1)... you do! It's fact(x-1)...

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