Thread: help with binary tree

This is the instruction for my assignment:
Write a program to process stock data. The stock data should be read from a text file containing the following data: stock code, stock name, amount invested (999.99), shares held, and current price.As each stock is read, insert it into a binary search tree (BST). The BST should be ordered on the stock code. (1½ marks)

After building the BST, display a menu with the following options: (1 mark)

(a) Display the BST in inorder traversal. Each display should contain an appropriate heading and column captions; (1 mark)

(b) Search for a stock using the stock code and print the data for the stock; (1 mark)

(c) Modify data for an existing stock; (2 marks)

(d) Write the data back to the file you used to build the tree in the beginning of the program execution, and stop the program. (1½ marks)

I have written the code but currently having problem with loading the list of stock stored in the file. The function of loading the code and inserting the stock into a binary tree are as follows:

Code:

void load(void)
{
	STOCK *info;
	FILE *inp;

	inp=fopen("stock.txt","r");
	if(!inp)
	{
		printf("Cannot open file.\n");
		exit(1);
	}

	//free any previously allocatd memory
	while(root)
	{
		info=root->left;
		free(info);
		root=info;
		info=root->right;
		free(info);
	}

	root=NULL;

	printf("\nLoading File.\n");
	while(!feof(inp))
	{
		info=(STOCK*)malloc(sizeof(STOCK));
		if(!info)
		{
			printf("Out of memory");
			exit(1);
		}

		while((fscanf( inp," %[^\n]", &info->stockCode))!=EOF)
		{
			fscanf( inp," %[^\n]", &info->stockName);
			fscanf( inp," %[^\n]", &info->amountInvested);
			fscanf( inp," %[^\n]", &info->sharesHeld);
			fscanf( inp," %[^\n]", &info->currentPrice);
			root=stree(root, info);
		}
	}


	if (fclose(inp)==EOF)
		{
			printf ("Error in closing file.\n");
			exit (105);
		}
		else 
		{
			printf ("File is successfully loaded.\n");
		}
	system("pause");
	system("cls");
}

Code:

STOCK *stree(STOCK *r, STOCK *n)
{
	if(!r)
	{
		n->left=NULL;
		n->right=NULL;

		if(!root)
			return n;
		
		if(strcmp(n->stockCode,root->stockCode) <0)
			root->left=n;
		else
			if(strcmp(n->stockCode,root->stockCode) >0)
				root->right=n;
		return n;
	}

	if(strcmp(r->stockCode, n->stockCode) <0)
		r=stree(r,r->right,n);
	else
		if(strcmp(n->stockCode,root->stockCode) >0)
			r=stree(r,r->left,n);

	return r;
}

I couldn't find the mistake where it only print out the last item. Any advise?
I attached the full coding as well.
Thanks.

There are a ton of things wrong with your code:

1) Never flush stdin or any stream for that matter. That behavior is undefined. Beginners use fflush way to happily.

2) Don't loop around feof(). Search the faq of this site for more info on that.

3) This sequence of instructions makes no sense:

free(info);
root = info;

4) You are misusing pointers quite a lot. Most times you just fail to allocate memory before using them or make them POINT TO SOMETHING that already exists.

These are a few things to look for right now.

I was just able to do this assignment after my test was over.

Originally Posted by Overworked_PhD

You aren't correctly free()ing the memory. What you need is a post order traversal in order to free() the nodes on your tree.

I tried creating a function like that, but it gives an error of info not initialized.

Code:

void sdestroy(STOCK *p)
{
 if(p != NULL) {
  sdestroy(p->left);
  sdestroy(p->right);

  free(p);
 }
}

The assignment is mostly done. The problem I having now is the error occured after I modify(delete and add) a stock detail and tried to view it. I attached the code here.

Of course, any advise to improve my code are welcome.

@MK27,claudiu,Overworked_PhD
Thanks for your help.