Binary Tree Traversal Using Recursive and Non Recursive Function in C

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

typedef struct bint
{
int data,flag;
struct bint *left,*right;
}node;

node * create(node *r,int d)
{
if(r == NULL)
{
r = (node *)malloc(sizeof(node));
r->data = d;
r->left = r->right = NULL;
}
else
{
if(r->data <= d)
r->right = create(r->right,d);
else
r->left = create(r->left,d);
}
return r;
}




void inorder(node *r)
{
if(r != NULL)
{
inorder(r->left);
printf("%d\t",r->data);
inorder(r->right);
}
}

void non_in(node *r)
{
int top=0;
node *s[20],*pt=r;
s[0]=NULL;
while(pt != NULL)
{
s[++top] = pt;
pt = pt->left;
}
pt = s[top--];
while(pt != NULL)
{
printf("%d\t",pt->data);
if(pt->right != NULL)
{
pt = pt->right;
while(pt != NULL)
{
s[++top] = pt;
pt = pt->left;
}
}
pt = s[top--];
}
}



void preorder(node *r)
{
if(r != NULL)
{
printf("%d\t",r->data);
preorder(r->left);
preorder(r->right);
}
}

void non_pre(node *r)
{
int top=0;
node *s[20],*pt=r;
s[0]=NULL;
while(pt != NULL)
{
printf("%d\t",pt->data);
if(pt->right != NULL)
s[++top] = pt->right;
if(pt->left != NULL)
pt = pt->left;
else
pt = s[top--];
}
}

void postorder(node *r)
{
if(r != NULL)
{
postorder(r->left);
postorder(r->right);
printf("%d\t",r->data);
}
}

void non_post(node *root)
{
node *stack[100];
int top=-1;
node *temp=root;
while(temp!=NULL)
{
while(temp!= NULL)
{
top++;
stack[top] = temp;
temp = temp->left;
}
label:temp =stack[top];
top--;
if(temp->flag==1)
{
printf("%d\t",temp->data);
break;
}
else
{
temp->flag=1;
top++;
stack[top] = temp;
temp=temp->right;
}
}
if(top>=0)
goto label;
}



void main()
{
 int d;
 char ch = 'Y';
 node *head = NULL;
 clrscr();
 while(toupper(ch) == 'Y')
 {
  printf("\n Enter the item to insert");
  scanf("%d",&d);
  head = create(head,d);
  printf("\n Do you want to continue(y/n)");
  fflush(stdin);
  ch = getchar();
 }
 printf("\ninorder recursive\n");
 inorder(head);
 printf("\ninorder non recursive\n");
 non_in(head);

 printf("\n\n");
 printf("\npostorder rrecursive\n");
 postorder(head);
 printf("\npostorder non recursive\n");
 non_post(head);

 printf("\n\n");
 printf("\npreorder recursive\n");
 preorder(head);
 printf("\npreorder non recursive\n");
 non_pre(head);
 getch();

}









Any problem in program please comment .......