recursive ?

This is a discussion on recursive ? within the C Programming forums, part of the General Programming Boards category; Given this snippet i know it sets the first element of the array A to zero but what about the ...

  1. #1
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    Question recursive ?

    Given this snippet i know it sets the first element of the array A to zero but what about the rest of the arrays dont they increase while the size decrements untilz size is 0?

    Code:
    void Mystery (int A[ ], int size)
    {
          if (size > 0){A[0] = 0; Mystery (A+1, size -1);}
    }

  2. #2
    Math wizard
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    a[0] will indeed only set the first element. You need either a variable in the brackets or some other numbers as well (and sometimes even some math inside like "ImageData[Row*TotalColumns+Column] = 5;").
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  3. #3
    Deathray Engineer MacGyver's Avatar
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    It's just setting each element in the array to 0. Trace it all on paper.

    Assuming the call is something like this:

    Code:
    int array[10];
    
    ...
    
    Mystery(array,10);
    First few iterations you'll have this:

    Code:
    Mystery is called: A points at array[0], size = 10
    (size > 0) is true.
    A[0] = 0;  This means array[0] = 0 in main()
    Mystery is then called with A + 1 and size - 1.
    Code:
    Mystery is called: A points to array[1], size = 9
    (size > 0) is true
    A[0] = 0;  array[1] = 0 in main()
    Mystery is then called with A + 1 and size - 1
    Code:
    Mystery is called: A points to array[2], size = 8
    (size > 0) is true
    A[0] = 0; array[2] = 0 in main()
    Mystery is then called with A + 1 and size - 1
    A is just really a pointer. It's not really an array, although it can behave just like one in many ways. It's important to realize that just because A[0] is set to 0, doesn't mean that array[0] is what will be changed.

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    Thanks you guys shood be c professors your make me understand better than my instructors

  5. #5
    Woof, woof! zacs7's Avatar
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    Maybe they are C professors?

    Also if your going to post 3 topics simultaneously, consider one posting them in one topic?

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    Question reply

    Quote Originally Posted by zacs7 View Post
    Maybe they are C professors?

    Also if your going to post 3 topics simultaneously, consider one posting them in one topic?
    easy does it I didnt mean to make u upset

  7. #7
    and the hat of int overfl Salem's Avatar
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    Ugly recursion
    element ?
    Considering that they were all basically the same question, once you actually understood recursion from one thread, figuring out the answers to all the others would have been a lot easier.
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