Program Overflow: Troubleshooting Tips

[ma12]

my program is not working properly after taking values it gets overflow

#include<stdio.h>
#include<conio.h>

void insert(struct node**, int);
struct node *ptr;

struct node
{
int data;
struct node *right;
struct node *left;
};


void main()
{
int will , i , num;
ptr = NULL;
ptr -> data = NULL;
printf("Enter the Number");
scanf("%d", &will);

for(i=0; i<will; i++)

{
printf("Enter the Item",&num);
insert(&ptr, num);
}
getche();
}



void insert(struct node **p, int num)
{

if( (*p) == NULL)
{
printf("Leaf node created");
(*p) -> left = NULL;
(*p) -> right = NULL;
(*p) -> data = num;
return;
}
else
{
if( num==(*p) -> data)
printf("Entered repeated values rejected");
return;
}

if(num < (*p) -> data)
{
printf("directed to left ");
insert ( &((*p) -> left) ,num);
}
else
{
printf("Directed to right");
insert( &((*p) -> right), num);
}


return;
}

 

[Borek]

Overflow of what, in which line.

 

[ma12]

in void insert

if(num < (*p) -> data)
{
printf("directed to left ");
insert ( &((*p) -> left) ,num);
}
else
{
printf("Directed to right");
insert( &((*p) -> right), num);
}

 

[Borek]

What does p point to?

And if you think the answer is "struct node", check out your code.

 

[rcgldr]

I don't see any mallocs() to allocate space for the structures.

 

[Coin]

Overflow probably means stack overflow. This usually means you got into an infinite recursion loop. In your code this is possible if you got into a situation where *p is never equal to NULL in insert(). If this happened insert() would keep calling itself forever, every call to insert() pushes a frame on the stack, eventually the stack overflows. One reason this might have happened is if you built a tree incorrectly such that there is a loop in it.

Also roger is right, if you ever somehow DID get to your "leaf node created" termination condition you'd instantly crash. You establish *p is NULL, then you assign to *p->left. If you write to or read from a null pointer you will crash (but the crash probably would not describe itself as an "overflow").