any ideas??

[seeks]

ok i've got my program to work but i need to add a functon that would be able to delete a node from the tree and give an error message when the user is trying to delete a node that isn't already present,i also have to take into account wether the node to be deleted has one,two,or no children
can anyone help?

this is my program:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define WORD_SIZE 30

/*
   program to read a set of words from a file, store them in a binary
   search tree and then preform an in-order traversal of the tree
   during traversal contents of nodes are displayed - word and count

   assumes potential duplicates in original file; only writes one copy
   back
*/

typedef struct Treenode
        {
	char word[WORD_SIZE];
	int count;

	struct Treenode *left;
	struct Treenode *right;
        } Treenode;

Treenode* new_node(Treenode*, char*);
void inorder(Treenode*);
void to_file_preorder(Treenode*, FILE*);
void menu();
void check_choice(Treenode* tree, char);

int main()
   {
   char	str[30];
   FILE* fptr;
   int check =0;
   char ch;

   Treenode* root =NULL;
	

   if ( (fptr = fopen("test.txt","r")) == NULL)
       {
       fprintf(stderr, "Error in opening file test.txt");
       return(0);
       }
	
   while(fscanf(fptr, "%s", str) != EOF)
        root = new_node(root, str);

   menu();
   scanf(" %c", &ch);

 
   while ((ch != 'e') && (ch != 'E'))
	{
	check_choice(root, ch);	
	menu();
        scanf(" %c", &ch);
        }



   fclose(fptr);

   if ( (fptr = fopen("test.txt","w")) == NULL)
       {
       fprintf(stderr, "Error in opening file test.txt for writing");
       return(0);
       }
   to_file_preorder(root, fptr);

   return(1);
   }


Treenode* new_node(Treenode* root, char word[30])
     {
     if(root == NULL)
	{
	root = (Treenode *) malloc(sizeof(Treenode));
	strcpy(root->word, word);		
	root->left = NULL;
	root->right = NULL;
	root->count = 1;
	}
	
	else
	   {
	   if((strcmp(word,root->word))==0)
		{
                root->count++;
		}
		else if((strcmp(word,root->word)) < 0)
		    {
		    root->left = new_node(root->left, word);
		    }
		else if((strcmp(word,root->word)) > 0)
		    {
		    root->right = new_node(root->right, word);
		    }
	    }
       return(root);
     }

void search(Treenode *root, char *term)
	{
	int l;

	if (root == NULL)
		{
		printf("Term not found\n");	
		return;
		}
	else if ((l = strcasecmp (root->word, term)) == 0)
		{
		printf("Term found in tree\n");
		return;
		}
	else if	(l > 0)
		search(root->left, term);
	else 
		search(root->right, term);
	}

void inorder(Treenode* root)
    {
	if(root != NULL)
	{
		inorder(root->left);
		printf("\n %s %d",root->word, root->count);
		inorder(root->right);
	}
    }

void  to_file_preorder(Treenode *root, FILE *fptr)
	{
	if (root != NULL)
		{
		to_file_preorder(root->left, fptr);
		fprintf(fptr, "%s ",root->word);
		to_file_preorder(root->right, fptr);
		}
	}


void menu()
	{
	
	printf("\n\tExit program (e)\n");
	printf("\tDisplay tree (d)\n");
	printf("\tSearch tree for string (s)\n");
	printf("\tAdd new string to tree (a)\n");
	return;
	}

void check_choice(Treenode *tree, char choice)
	{
	char term[WORD_SIZE];

	switch(choice)
		{
		case 'e' : printf("Exiting ...\n");
		      break;
		case 'd' : inorder(tree);
			   break;
                case 's' : printf("Please enter search term\n");
			   scanf ("%s", term);
			   search(tree, term);
			   break;
                case 'a' : printf("Please enter term to be added\n");
			   scanf ("%s", term);
			   tree = new_node(tree, term);
			   break;
		}
	}