Pointer Panic

[Moghammed]

Hi all,

I'm writing a program that implements a binary search tree datastructure using pointers.

However, i have encountered a problem i can't seem to figure out...

void bst::addnode(int val)
{
	findaspot(val);
	node* newnode;
	if(theplacetobe == root)
	{
		cout << "root is tha place to be" << endl;
		newnode = root;
	}
	else
	{
		if(val >= theplacetobe->value)
		{
			newnode = theplacetobe->right;
		}
		else
		{
			newnode = theplacetobe->left;
		}
	}
	newnode = new node;
	newnode->value = val;
	cout << endl <<"newnode value:" << newnode->value << endl;
	cout << "root value: " << root->value << endl;
}

void findspot(int) sets pointer theplacetobe to the leaf of the tree where i want to add the new node. (for those who don't know: a binary search tree is a tree in wich new nodes have at most 2 children, the right one bigger than the node itself, the left one smaller.)

now here's the problem:

when the first node is added (and newnode therefore == root), newnode->value is equal to val
root->value, however is nonsense (somewhere around 9.000.000).

Why does this happen, when i have set newnode to be equal to root?

Many thanks in advance!!

-Mohammed

[treuss]

Please edit your post and add code tags around your code. Read through the FAQ (via the Before you Post link) for details.

[MrViggy]

Hard to read without code tags, but it appears that you are setting newnode to a new node:

newnode = new node;

This is most definitely not the same node as root.

Viggy

[Peter_APIIT]

This link may help.

http://peterapiit.blogspot.com/

[Moghammed]

thx for your replies!!

sorry i didn't put the code in codetags, posted it too quickly and then couldn't find it back :S

I've solved it though..

for anyone interested:

newnode = root;

obviously sets the pointers to the same memoryaddress

however, this:

newnode = new node;

sets newnode to a new address, which is kindof logical, as you can't be sure there is enough unreserved memory for the new object at the memory address newnode was pointing to.

a simple

root = newnode;

after the creation of the new node solved the problem.


Greetz. Mo