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

#define OK 1
#define ERROR 0
#define NULL 0
#define OVERFLOW -2

typedef int Status;
typedef char TElemType;

/*二叉树的二叉链表存储表示*/
typedef struct BiTNode{
    TElemType data;
    struct BiTNode *lchild, *rchild;    //左右孩子指针
}BiTNode, *BiTree;

/*建立二叉链表*/
Status CreateBiTree(BiTree &T){
    //按先序次序输入二叉树中结点值，空格表示空树
    //构造二叉链表表示的二叉树
    char ch;
    scanf("%c",&ch);
    
    //ch=getchar();
    if(ch==' ')
        T=NULL;
        
    else
    {
        if(!(T=(BiTNode*)malloc(sizeof(BiTNode)))) exit(OVERFLOW);
        T->data=ch;
        CreateBiTree(T->lchild);
        CreateBiTree(T->rchild);
    }
    return OK;
}

/*打印二叉树的内容*/
Status PrintElement(char ch)
{
    printf("%c",ch);

    return OK;
}

/*先序遍历二叉树，递归算法*/
Status PreOrderTraverse(BiTree T,Status(*PrintElement)(TElemType e))
{
    if(T)
    {
        if(PrintElement(T->data))
            if(PreOrderTraverse(T->lchild,PrintElement))
                if(PreOrderTraverse(T->rchild,PrintElement))
                    return OK;
        return ERROR;
    }
    else return OK;
}
/*中序遍历二叉树，递归算法*/
Status InOrderTraverse(BiTree T,Status(*PrintElement)(TElemType e))
{
    if(T)
    {
        if(InOrderTraverse(T->lchild,PrintElement))
            if(PrintElement(T->data))
                if(InOrderTraverse(T->rchild,PrintElement))
                    return OK;
        return ERROR;
    }
    else return OK;
}

/*后序遍历二叉树，递归算法*/
Status PostOrderTraverse(BiTree T,Status(*PrintElement)(TElemType e))
{
    if(T)
    {
        if(PostOrderTraverse(T->lchild,PrintElement))
            if(PostOrderTraverse(T->rchild,PrintElement))
                if(PrintElement(T->data))
                    return OK;
        return ERROR;
    }
    else return OK;
}


int main()
{    BiTree T;
    printf("请输入二叉树:");
    printf("\n");
    CreateBiTree(T);
    
    printf("先序遍历:");
    printf("\n");
    PreOrderTraverse(T,PrintElement);
    
    printf("\n");
    printf("中序遍历:");
    printf("\n");
    InOrderTraverse(T,PrintElement);
    
    printf("\n");
    printf("后序遍历:");
    printf("\n");
    PostOrderTraverse(T,PrintElement);
    printf("\n");
    return 0;

}

可以输入 ABC##DE#G##F###
进行测试 注"#"为空格

good