如何修改一下代码，使其能线索化二叉树：（8）19（（5）11（（2）6（4）））
// a.cpp : Defines the entry point for the console application.
//

// tbt.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include "stdio.h"
#include "stdlib.h"

typedef struct node //二叉树结点的结构
{
    char   ch;
    struct node *lchild, *rchild;
    int    ltag, rtag;
}Bnode;

Bnode * InitRoot()
{
    Bnode * root;
    root = (Bnode *) malloc(sizeof(Bnode));
    root->lchild = NULL;
    root->rchild = NULL;
    return root;
}

Bnode * CreateBiTree(Bnode ** T)
{
    char ch;
   
    fflush(stdin);
    ch = getchar();
   
    if (ch=='#'){
        * T = NULL;
        return NULL;
    }
    else{
        Bnode * temp;
        if (!(temp= (Bnode *)malloc(sizeof(Bnode)))) return NULL;
        temp->ch= ch;
        * T = temp;
        CreateBiTree(&(temp->lchild));
        CreateBiTree(&(temp->rchild));
    }
    return *T;
}

void InOrder(Bnode * root)
{
    if (root == NULL) return;
    InOrder(root->lchild);
    printf("%c ", root->ch);
    InOrder(root->rchild);
}

void Destory(Bnode ** root)
{
    if ((*root) != NULL &&  ((*root)->lchild != NULL))
    Destory(&((*root)->lchild));
    if ((*root) != NULL &&  ((*root)->lchild != NULL))
    Destory(&((*root)->lchild));
    free(root);
}

void InThread(Bnode * current, Bnode ** pre)
{
    if (current != NULL){
        InThread(current->lchild,pre);
   
        if (current->lchild == NULL)
        {
            current->ltag = 1;
            current->lchild = * pre;
        }
        else
            current->ltag = 0;
        if (current->rchild != NULL) current->rtag = 0;
        if ((*pre)->rchild == NULL)
        {
            (*pre)->rtag = 1;
            (*pre)->rchild = current;
        }
        else  current->rtag = 0;
        (*pre) = current;
        InThread(current->rchild, pre);
    }
}

void CreateInThread(Bnode ** root)
{
    Bnode * t = * root;
    Bnode *current, *pre;
    *root = (Bnode *)malloc(sizeof(Bnode));
    pre = * root;
    if (t==NULL)
    {
        (*root)->ltag = 0;
        (*root)->rtag = 1;
        (*root)->lchild = *root;
        (*root)->rchild = *root;
    }
    else
    {
        current = t;
        (*root)->lchild = t;
        (*root)->ltag = 0;
        InThread(current, &pre);
        pre->rchild = *root;
        pre->rtag = 1;
        (*root)->rchild = pre;
        (*root)->rtag = 1;
    }
}

int main(int argc, char * argv[])
{
    Bnode * root, * head;
    CreateBiTree(&root);

    InOrder(root);
   
    CreateInThread(&root);
   
    //Destory(&root);
   
    printf("Hello World!\n");
    return 0;
}