#include "stdio.h"
typedef char Datatype;
typedef struct threaded_tree *pt_threaded;
typedef struct threaded_tree {
	short  int  left_thread;
    pt_threaded left_child;  
    Datatype  data;
    pt_threaded right_child;
    short  int  right_thread;
};
pt_threaded succ( pt_threaded tree)
{ //在樹中找到結(jié)點(diǎn)的中序前驅(qū)
   pt_threaded temp;
   temp = tree->right_child;
   if ( !tree->right_thread )
	while( !temp->left_child )
		temp = temp->left_child;
   return temp;
}
void inorder(pt_threaded tree)
{   //中序遍歷線索二叉樹
   pt_threaded temp=tree;
   for(; ;){
	temp = succ (temp);
	if (temp = tree) break;
	printf ("%3c", temp->data);
   }
}

void main()
{
	pt_threaded p;
	inorder(p);
}