请各位高手看看是怎么了

#include <conio.h>
#include<stdio.h>
#include<stdlib.h>
#define maxsize 100
typedef struct node{
char data;
struct node *lchild,*rchild;
}bt;
createbt(bt **T)
 {char ch;
 scanf ("%c",&ch);
 if(ch==' ') *T=NULL;
  else {*T=(bt *)malloc(sizeof (bt));
         (*T)->data =ch;
          createbt(&((*T)->lchild)) ;
          createbt(&((*T)->rchild)) ;
        }
 }

preorder (bt *t)
   { printf("%c",t->data);
     preorder(t->lchild);
     preorder(t->rchild);
     getch();
     }
inorder (bt *t)
   { preorder(t->lchild);
     printf("%c",t->data);
     preorder(t->rchild);
     }
 postorder (bt *t)
   { preorder(t->lchild);
     preorder(t->rchild);
     printf("%c",t->data);
     }
main()
{
 int i,j,a;
 bt *h;
 createbt(&h);

window(0,0,5,5);
textbackground(4);
textcolor(0);
clrscr();
gotoxy(10,10) ;
for (i=5;i<=20;i++)  /*左右框*/
   { gotoxy(10,i);
     printf("*");
     gotoxy(70,i);
     printf("*");
  }
for (j=10;j<=70;j++)
   { gotoxy(j,5);
     printf("*");
     gotoxy(j,20);
    printf("*"); /*上下框*/
  }
gotoxy(33,7);
printf("  1 preorder ") ;
gotoxy(33,11);
printf("  2 inorder ") ;
gotoxy(33,15);
printf("  3 postorder ") ;
gotoxy(35,22);
printf("input number 1-3:");
scanf("%d",&a) ;
switch (a)
  {
  case 1:  preorder(&h); break;
  case 2:  inorder(&h); break;
  case 3:  postorder(&h) ; break;
  }
getch();
}

怎么都没人回呀