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Homework Help: C++ Binary Search Tree preorder printing tree problem

  1. Dec 5, 2011 #1
    Q.When run the program should ask for an input file containing integer keys to be added to the
    search tree. The file will contain one key per line. Add these keys in the order given in the file to
    the search tree. Then print the entire tree using preorder traversal i.e., root, left-child, right-child.
    The output must be indented properly to show the appropriate levels.
    For example, if the input keys are 4, 3, 7, 8, 6. The output should look like this
    <2 spaces>3
    <2 spaces>7
    <3 spaces>6
    <3 spaces>8

    I have made the tree. How do I go about printing it as shown above?? ANY help would highly be appreciated.
    Last edited: Dec 5, 2011
  2. jcsd
  3. Dec 5, 2011 #2
    This is my code. Sorry i could not include comments :(
    Code (Text):

    #include <iostream>
    #include <fstream>
    #include <istream>
    #include <string>
    using namespace std;

    struct node
        int data;
        int depth;
        struct node *left, *right;

    void insert(struct node *r, struct node *p)
        if ((r->right == NULL) && p->data > r->data)
        r->right = p;
        else if ((r->right != NULL) && p->data> r->data)
        insert(r->right, p);
        if ((r->left == NULL) && p->data< r->data)
        r->left = p;
        else if ((r->left != NULL) && p->data< r->data )
        insert(r->left, p);
    void tree(struct node *r, int c)
        int top, flag;
        struct node *w, *stack[20];
        if (r != NULL)
            if (c != 4)
                if (c == 1)
                tree(r->left, c);
                if (c == 2)
                tree(r->right, c);
                if (c == 3)

    void main()
        int choice, c, i, flag,z,j=1;
        char temp = 'N', temp1[15];
        struct node *s, *root, *r, *q;
        root = NULL;

        string line;
        string v;
        cout<<"Enter an unspaced string of path to the file\n (ALL FOLDER NAMES AS WELL AS FILENAMES MUST NOT CONTAIN SPACES)\n"<<endl;
        int a;

        fstream myfile (v);
        if (myfile.is_open()) //if the file is open
            while (! myfile.eof() ) //while the end of file is NOT reached
                int TempNumOne=line.size();
                s = (node*)malloc(sizeof(struct node));
                s->left = NULL;
                s->right = NULL;
                int pp=atoi(line.c_str());

                if (root == NULL)
                    root = s;
                    insert(root, s);
                if (root == NULL)
                    cout<<("Tree Not Started Yet");
                    tree(root, 1);
                cout<<("\n Press Any Key To Continue......");
    Last edited by a moderator: Dec 5, 2011
  4. Dec 5, 2011 #3


    Staff: Mentor

    When you enter code, please surround it with [noparse]
    Code (Text):
    [/noparse] tags. This makes your code easier to read by preserving your indentation.
  5. Dec 6, 2011 #4
    Clean up your insert routine to only test p->data against r->data once.

    Think about using the (currently unset) depth variable in nodes to control spaces.
    What is the point of "c" in routine "tree"?
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