Weird error in binary search tree [closed]

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 11 years ago.

#include <iostream>
using namespace std;
#define YES 1
#define NO 0

class tree
{
    private:

    public:
        struct leaf
        {
            int data;
            leaf *l;
            leaf *r;
        };
        struct leaf *p;
        tree();
        ~tree();
        void destruct(leaf *q);
        tree(tree& a);
        void add(int n);
        void transverse();
        void in(leaf *q);
        void pre(leaf *q);
        void post(leaf *q);
        leaf*  createBST(int *preOrder, int* inOrder, int len);     
};      
tree::tree()
{
    p=NULL;
}
tree::~tree()
{
    destruct(p);
}
void tree::destruct(leaf *q)
{

}

void tree::transverse()
{
    int c;
    cout<<"\n1.InOrder\n2.Preorder\n3.Postorder\nChoice: ";
    cin>>c;
    switch(c)
    {
        case 1:
            in(p);
            break;

        case 2:
            pre(p);
            break;

        case 3:
            post(p);
            break;
    }
}
void tree::in(leaf *q)
{
    if(q!=NULL)
    {
        in(q->l);
        cout<<"\t"<<q->data<<endl;
        in(q->r);
    }

}
void tree::pre(leaf *q)
{
    if(q!=NULL)
    {
        cout<<"\t"<<q->data<<endl;
        pre(q->l);
        pre(q->r);
    }

}
void tree::post(leaf *q)
{
    if(q!=NULL)
    {
        post(q->l);
        post(q->r);
        cout<<"\t"<<q->data<<endl;
    }

}



tree::leaf* tree::createBST(int *preOrder, int* inOrder, int len)
{
    int i;
    tree::leaf *bst = new tree::leaf;
//  tree bst;
//  if(len < 0)
//      {//bst = NULL;
//      return bst;}

    bst->data = *preOrder;
    for(i = 0; i < len; i++)
        if(*(inOrder + i) == *preOrder)
        break;
    if(i>=0)    
        bst-&g开发者_开发百科t;l = createBST(preOrder + 1, inOrder, i);
    if((len-i-1) >=0)
        bst->r = createBST(preOrder + i +1, inOrder + i + 1, len-i-1);
    return bst;

}

int main()
{


    tree bst;
    int pre_data[] = {20,8,4,12,10,14,22};
    int in_data[] = {4,8,10,12,14,20,22};
    bst.p = bst.createBST(pre_data, in_data, 7);
    bst.transverse();

    return 0;
}

The main problem is in function

  tree::leaf* tree::createBST(int *preOrder, int* inOrder, int len)

Note: I've posted two questions about this. Because I modified my code a lot I started a fresh post.

---

I believe the error is that you have no terminating condition for your recursion. Consider the case where len == 0, you will execute this line of code:

bst->l = createBST(preOrder + 1, inOrder, i);

This will pass in a length of 0 and the same thing will happen again. This is infinite recursion, and will cause a segmentation fault.

I think your problem is solved by adding this to beginning of createBST:

if(len == 0)
    return NULL;