A Binary Search Tree (BST)

#include<stdio.h>
#include<conio.h>
#include<malloc.h>
#include<process.h>
struct node{
	int info;
  struct node *right;
  struct node *left;
};
typedef struct node *BST;
typedef struct node node;
BST makeempty(BST t)
{
 	if (t!=NULL) {
  	makeempty(t->left);
   makeempty(t->right);
   free(t);
  }
  return NULL;
}

BST find(BST t, int x)
{
 	if (t==NULL) return NULL;
  if (x<t->info) return find(t->left,x);
  else
  if (x>t->info) return find(t->right,x);
  else
  return t;
}

BST findmin(BST t)
{
	if(t==NULL) return NULL;
  else
	if(t->left==NULL) return t;
  else return findmin(t->left);
}

BST findmax(BST t)
{
	if(t==NULL) return NULL;
  else
	if(t->right==NULL) return t;
  else return findmax(t->right);
}

BST insertnode(BST t, int x)
{
  if(t==NULL) {
  	t=(node*)malloc(sizeof(node));
   if(t==NULL) printf("\n Out of Space !!");
   else {
   	t->info = x;
     t->left = t->right = NULL;
   }
  }
  else
  if (x<t->info) {
  	t->left=insertnode(t->left,x);
  }
  else
  if (x>t->info) {
  	t->right=insertnode(t->right,x);
  }
  return t;
}

BST deletenode(BST t, int x)
{
	BST tmpcell;
	if(t == NULL) {
  	printf("\n Cannot Delete!! No Such Value Found");
  }
  else
  if(x < t->info) t->left = deletenode(t->left,x);
  else
  if(x > t->info) t->right = deletenode(t->right,x);
  else
 	if(t->right && t->left){
  	tmpcell = findmin(t->right);
   t->info = tmpcell->info;
   t->right = deletenode(t->right,tmpcell->info);
  }
  else {
  	tmpcell = t;
   if(t->left == NULL) t = t->right;
   else if(t->right == NULL) t = t->left;
   free(tmpcell);
   printf("\n Value Successfully Deleted.");
  }
  return t;
}

void printtree_asc(BST t)
{
 	if (t!=NULL) {
  	printtree_asc(t->left);
   printf("\n %d",t->info);
   printtree_asc(t->right);
  }
}

void printtree_desc(BST t)
{
 	if (t!=NULL) {
  	printtree_desc(t->right);
   printf("\n %d",t->info);
   printtree_desc(t->left);
  }
}
main()
{
	BST tree, pos;
  char ans;
  int val;
  tree=NULL;
  while(1){
  	printf(" Binary Search Tree (BST)");
  	printf("\n\n [1].\tInsert\n");
   printf(" [2].\tDelete\n");
   printf(" [3].\tMake Empty\n");
   printf(" [4].\tFind Minimum\n");
   printf(" [5].\tFind Maximun\n");
   printf(" [6].\tSearch\n");
   printf(" [7].\tPrint Ascending\n");
   printf(" [8].\tPrint Descending\n");
   printf(" [9].\tExit\n\n");
   printf(" Enter Choice: ");
 		ans = getche();
   switch(ans)
   {
   	case '1':
     {
     	printf("\n Enter Value: ");
     	scanf("%d",&val);
     	tree=insertnode(tree,val);
     }
     break;

     case '2':
     {
     	if(tree!=NULL) {
     	printf("\n Enter Value to be Deleted: ");
     	scanf("%d",&val);
     	tree=deletenode(tree,val);
     }
     else printf("\n Cannot Delete!! Empty BST!!");
     getch();
     }
     break;

     case '3':
     {
     	tree = makeempty(tree);
     	printf("\n BST is now Empty!!");
     	getch();
     }
     break;

     case '4':
     {
     	pos=findmin(tree);
     	if (pos!=NULL)
     		printf("\n Minimum Value: %d",pos->info);
     	else
     		printf("\n Empty BST!! No Minimum Value.");
     	getch();
     }
     break;

     case '5':
     {
     	pos=findmax(tree);
     	if (pos!=NULL)
     		printf("\n Maximum Value: %d",pos->info);
     	else
     		printf("\n Empty BST!! No Maximum Value.");
      getch();
     }
     break;

     case '6':
     {
     if (tree!=NULL) {
     	printf("\n Enter Value to be Searched: ");
     	scanf("%d",&val);
     	pos=find(tree, val);
     	if (pos!=NULL)
     		printf("\n %d is found in the BST",pos->info);
      else
     		printf("\n %d not found in the BST",val);
     }
     else {
     	printf("\n The BST is Empty!!");
     }
     getch();
     }
     break;

     case '7':
     {
     	if(tree!=NULL) {
     	clrscr();
     	printf("\n BST IN ASCENDING ORDER\n\n");
     	printtree_asc(tree);
     }
     else printf("\n Empty BST!!");;
     getch();
     }
     break;

     case '8':
     {
     	if(tree!=NULL) {
     	clrscr();
     	printf("\n BST IN DESCENDING ORDER\n\n");
     	printtree_desc(tree);
     }
     else printf("\n Empty BST!!");
     getch();
     }
     break;

     case '9':
     exit(0);
     default :
     {
     	printf("\n\n Choose from 1 to 9 only!!");
     	getch();
     }
     break;
   }
   clrscr();
  }
}