1．数据结构采用ltag和rtag标志域的二叉链表（线索链表）存储二叉树及线索。

2．输入数据

从键盘输入任意二叉树的前根排序序列，当某结点的左子树或右子树为空时，用“.”代替，输入内容为：

abd. .eh...cf.i..g..

输出中序线索化后各点所有内容，

注：(1)若lchild或rchild域为空，输出时用“－”表示。

(2)lchild域或rchild域的内容用他们所指结点的data域的值表示。

有哪位高手能帮助吗？应为对树真的不懂，太抽象了书上写的不具体好难理解

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

typedef struct node
{
char data;
struct node *lchild, *rchild;
int ltag, rtag;
}*Tree, Tnode;

static void CreateTree(Tree *T);
static void ThreadTree(Tree *T);
static void PrintThreadTree(Tree T);
static Tree NextNode(Tree curPtr);

int main(void)
{
Tree T = NULL;

CreateTree(&T);

ThreadTree(&T);

PrintThreadTree(T);

getch();
return 0;
}

static void CreateTree(Tree *T)
{
int ia;

ia = getchar();

if (ia == '/')
{
*T = NULL;
}
else
{
if (((*T) = (Tree)malloc(sizeof(Tnode))) == NULL)
{
exit(1);
}
(*T) -> data = ia;
(*T) -> lchild = (*T) -> rchild = NULL;

CreateTree(&(*T) -> lchild);
CreateTree(&(*T) -> rchild);
}
}

static void ThreadTree(Tree *T)
{
static Tree prePtr = NULL; /* prePtr = previous pointer */

if (*T != NULL)
{
ThreadTree(&(*T) -> lchild); /* thread left tree */
if ((*T) -> lchild == NULL)
{
(*T) -> ltag = 1;
}
if ((*T) -> rchild == NULL)
{
(*T) -> rtag = 1;
}

if (prePtr -> rtag == 1)
{
prePtr -> rchild = *T;
}
if ((*T) -> ltag == 1)
{
(*T) -> lchild = prePtr;
}

prePtr = *T;
ThreadTree(&(*T) -> rchild); /* thread right tree */
}
}

static void PrintThreadTree(Tree curPtr)
{ /* curPtr = current pointer */
while (curPtr -> lchild != NULL)
{
curPtr = curPtr -> lchild; /* search the first print node */
}

while (curPtr != NULL)
{
printf("%c -> ", curPtr -> data);

curPtr = NextNode(curPtr);
}
printf("NULL\n");
}

static Tree NextNode(Tree curPtr)
{
if (curPtr -> rtag == 1)
{
return curPtr -> rchild;
}
else
{
curPtr = curPtr -> rchild;
while (curPtr -> ltag != 1)
{
curPtr = curPtr -> lchild;
}

return curPtr;
}
}



这个在严蔚敏的《数据结构》上有，不过版主确实厉害！