Please debug this

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November 5th, 2012, 02:53 AM

sakura66

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Join Date: Nov 2012

Posts: 2

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Please debug this

Code:

#include<stdio.h>
#include<stdlib.h>
 
 
int CompareIntegerDefault(void *data1, void *data2)
{
     
    if(*(int *)data1>*(int *)data2)
        return (1);
    else if(*(int *)data1==*(int *)data2)
        return (0);
    else
        return (-1);
}
typedef struct AVLTreeNode
{
    void *data ;
    int balfact ;
     
    struct AVLTreeNode *left ;
    struct AVLTreeNode *right ;
} AVLTreeNode,*AVLTreeNodePtr;
 
 
typedef struct ContainerHandle
{
    struct AVLTreeNode *AVLRoot;
    //int h;
}ContainerHandle_t,*ContainerHandlePtr_t;
int h;
void buildtree (AVLTreeNodePtr *root, void *data  )
{
    struct AVLTreeNode *node1, *node2 ;
 
 
    if ( !root )
    {
        (*root) = ( struct AVLTreeNode * ) malloc ( sizeof ( struct AVLTreeNode ) ) ;
        (*root) -> data = data ;
        (*root) -> left = NULL ;
        (*root) -> right = NULL ;
        (*root) -> balfact = 0 ;
        h=1;
        return ;
    }
   
}
 
 
ContainerHandlePtr_t List;
 
 
int main()
{
    int a;
    List=(ContainerHandlePtr_t)malloc(sizeof(ContainerHandle_t));
    List->AVLRoot=NULL;
    a=5;
    buildtree ( &(List->AVLRoot),&a);    
    printf("%d",*(int *)(List->AVLRoot->data));
    return 0;
}

It is not giving the expected result-5
Please help me debug this. Thanks!

November 5th, 2012, 07:31 AM

Schol-R-LEA

Commie Mutant Traitor

Dev Shed Intermediate (1500 - 1999 posts)

Join Date: Jun 2004

Location: Norcross, GA (again)

Posts: 1,785

Time spent in forums: 1 Month 2 Weeks 2 Days 18 h 21 m 8 sec
Reputation Power: 1569

The problem is in the test for the validity of root in buildtree(). As it is, you are testing whether root is NULL, but you just assigned a value to root, namely, an uninitialized AVLTreeNodePtr. What you actually want to test is that pointer itself, so the correct test would be

Code:

    if ( !*root )

Mind you, this doesn't fix the problem; when I tried the code with just this change, the compiler complained that *(root) ->data was not a valid structure member. While I am not certain why this would be so, The workaround I found was to initialize a local pointer, set up all the data in it, and assign that pointer to *root:

Code:

void buildtree (AVLTreeNodePtr *root, void *data  )
{
    struct AVLTreeNode *new_tree = NULL;

    if ( !*root )
    {
        new_tree = ( struct AVLTreeNode * ) malloc ( sizeof ( struct AVLTreeNode ) ) ;
        if (new_tree != NULL)
        {
            new_tree -> data = data ;
            new_tree -> left = NULL ;
            new_tree -> right = NULL ;
            new_tree -> balfact = 0 ;
            h=1;
            *root = new_tree ;
        }
    }
}

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Please debug this

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