Move binary tree elements to stack

This is a discussion on Move binary tree elements to stack within the C Programming forums, part of the General Programming Boards category; Hello. I am trying to move binary tree elements to stack. I tried to move like this but i am ...

  1. #1
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    Move binary tree elements to stack

    Hello. I am trying to move binary tree elements to stack. I tried to move like this but i am getting empty stack still/.
    Code:
       void move(TreePtr current)
    {
         Stack start;
         Stack end;
         int D;
         if (current !=NULL)
         {
            move(current->left);
            D=current->element;
                    G=(Stack)malloc(sizeof(stack));
            end->number=D;
            end->next=start;
            start=end;
            move(current->right);
         }  
    }
    Last edited by krakatao; 04-09-2012 at 10:49 AM.

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    Several things:

    • Define "move binary tree elements to stack". There is more than one way to do it.
    • You don't provide us with crucial information like how TreePtr and Stack are declared or what G is.
    • Use descriptive variable names, not bizarro one-letter crap like D and G. Better yet, get rid of them. You don't need either of them as far as I can tell.
    • Don't use globals. Read this: Global Variables Are Bad.
    • Don't cast malloc. Read this: FAQ > Casting malloc - Cprogramming.com
    • If start and end are local variables, how do you plan to get them out of the function? You need to return them somehow.

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    "G" is "end" forgot to change when translated code.

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    It's hard to tell without seeing implementation details, but can you traverse your entire tree and print all node values or destroying the tree freeing all nodes? Can you build a stack by pushing values to it? If you know how to do these in isolation you can easily replace print with push as you traverse the tree.

  5. #5
    Algorithm Dissector iMalc's Avatar
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    Hint: You appear to be writing a "tree to rope" function.
    My homepage
    Advice: Take only as directed - If symptoms persist, please see your debugger

    Linus Torvalds: "But it clearly is the only right way. The fact that everybody else does it some other way only means that they are wrong"

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    I can print tree values and delete them. Also i can insert elements into stack but when i do like this it still does not work.
    Code:
    void move(TreePtr current)
    {
         Stack start;
         Stack end;
         int D;
         if (current !=NULL)
         {
            move(current->left);
            intoStack(start, current->element);
    
            move(current->right);
         }  
    }

  7. #7
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    Like I said earlier:
    Quote Originally Posted by anduril462 View Post
    • If start and end are local variables, how do you plan to get them out of the function? You need to return them somehow.
    As you have it, each call creates a separate start and end that exist only in that function, and disappear as soon as the function returns. Not only that, since they contain the result of a malloc, which you never free, you have a memory leak. You need to declare start and end outside your move function, and pass them in.

  8. #8
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    Now I understood. But how to pass them in?

  9. #9
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    Thanks already solved.
    Last edited by krakatao; 04-10-2012 at 01:38 AM.

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