binary tree with traversal! HELP!!

[khashastriya]

please help me to improve my program code in binary tree with traversal.the program must input of minimum 10 integers..
.here's my code
#include<iostream>
#include<conio.h>

using namespace std;
struct btree
{
struct btree *left;
struct btree *right;
int no;
};
void postorder(struct btree *trav);
void inorder(struct btree *trav);
void preorder(struct btree *trav);
struct btree * create(struct btree *trav);
int main()
{
struct btree *root=NULL;
char c;

while(1)
{
root=create(root);
cout<<"Do you want to continue : ";
cin>>c;
if(c=='n' ||c=='N')
break;
}
cout<<endl<<"Inoder is : ";inorder(root);
cout<<endl<<"Preorder is : ";preorder(root);
cout<<endl<<"Postorder is : ";postorder(root);
getch();
}
struct btree * create(struct btree *trav)
{
if(trav==NULL)
{
trav=new btree;
trav->right=NULL;
trav->left=NULL;
cout<<"Enter the no : ";
cin>>trav->no;
return(trav);
}
char choice;
cout<<"Enter the left or right child : ";
cin>>choice;
if(choice == 'r' || choice == 'R')
{
trav->right=create(trav->right);
}
if(choice=='l' || choice=='L')
{
trav->left=create(trav->left);
}
return(trav);
}
void inorder(struct btree *trav)
{
if(trav==NULL)
return ;
inorder(trav->left);
cout<<" "<<trav->no;
inorder(trav->right);
}
void preorder(struct btree *trav)
{
if(trav==NULL)
return;
cout<<" "<<trav->no;
preorder(trav->left);
preorder(trav->right);
}
void postorder(struct btree *trav)
{
if(trav==NULL)
return;
postorder(trav->left);
postorder(trav->right);
cout<<" "<<trav->no;
}