Recursion

This is a discussion on Recursion within the C Programming forums, part of the General Programming Boards category; I'm not very good at recursion - how would I write a program to show compound interest of 1%/month over ...

  1. #1
    Peaches
    Guest

    Lightbulb Recursion

    I'm not very good at recursion - how would I write a program to show compound interest of 1%/month over 12 months?
    I'm supposed to convert this factorial example:

    Code:
    #include<stdio.h>
    int factorial(long);
    
    int main(void)
    {
    int i;
    for (i=1; i<=10; i++)
        printf("%2d! = %ld\n", i, factorial(i));
    return (0);
    }
    
    int facotial(long num)
    {
    if (number <= 1)
        return (1);
    else
        return (number * factorial(number -1));
    }

  2. #2
    Skunkmeister Stoned_Coder's Avatar
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    Do you know how to work out compound interest mathematically?

    translate that into pseudocode and all will become clearer.
    Free the weed!! Class B to class C is not good enough!!
    And the FAQ is here :- http://faq.cprogramming.com/cgi-bin/smartfaq.cgi

  3. #3
    Peaches
    Guest
    Aaahh, recursion is starting to become clearer!

    Code:
    float interest(float n, int a)
    {
        if (a<=1)
            return (n * 1.01);
        else
            return (1.01 * interest(n, a-1));
    }
    Many thanks!

  4. #4
    Banned master5001's Avatar
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    The general rule is that if you can do something without recursion then you should use the non-recursive function. This can be done without recursion so I would change the code. But I'm a stickler for optimization.

  5. #5
    ggs
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    C > C++ duders ggs's Avatar
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    but recursion is pretty

    and readable, another good thing. take readable recursion unless you're an optimization sticklet ;D
    .sect signature

  6. #6
    moi
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    use the real formula for compound interest
    hello, internet!

  7. #7
    Visionary Philosopher Sayeh's Avatar
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    This is not a rebuttal to Master5001, it's just a response to this kind of quote, which I've seen posted numerous times over the years--

    The general rule is that if you can do something without recursion then you should use the non-recursive function.
    I was never much for following rules that were created by eggheads who don't really know how to program.

    Recursion is a perfectly valid programming method. The _only_ time you don't use it is if using it creates additional problems-- such as

    a) stack overflow
    b) performance decrease

    Do what MAKES SENSE, not what some zealot purist egghead thinks is right based on no understanding of reality.
    It is not the spoon that bends, it is you who bends around the spoon.

  8. #8
    moi
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    its all really irrelevant in this case, because the real compound interest forumula uses no loops or recursion.

    imo, a loop is usually easier to understand than recursion anyways, but use whatever fits the situation.
    hello, internet!

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