二叉树的基本操作和应用的问题

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

typedef struct node
{
    char data;
    struct node * LChild;
    struct node * RChild;
}biTnode,*biTree;

void preorder(biTree root)
{
    if(root!=NULL)
    {
        printf("%c",root->data);
        preorder(root->LChild);
        preorder(root->RChild);
    }
}

void inorder(biTree root)
{
    if(root!=NULL)
    {
        inorder(root->LChild);
        printf("%c",root->data);
        inorder(root->RChild);
    }
}

void postorder(biTree root)
{
    if(root!=NULL)
    {
        postorder(root->LChild);
        postorder(root->RChild);
        printf("%c",root->data);
    }
}

void GreatebiTree(biTree * bt)
{
    char ch;
    ch = getchar();
    if(ch == '#')
        *bt = NULL;
    else
    {
        *bt = (biTree)malloc(sizeof(biTnode));
        (*bt)->data = ch;
        GreatebiTree(&((*bt)->LChild));
        GreatebiTree(&((*bt)->RChild));
    }
}

int main()
{
    biTnode * bt;
    int num;
    printf("please enter this tree:\n");
    GreatebiTree(&bt);
    printf("┌────────────────────┐\n");
    printf("│   please choose one input the tree:    │\n");
    printf("│         1.preorder                     │\n");
    printf("│         2.inorder                      │\n");
    printf("│         3.postorder                    │\n");
    printf("└────────────────────┘\n");
    scanf("%d",&num);
    switch(num)
    {
        case 1:
            preorder(bt);
        case 2:
            inorder(bt);
        case 3:
            postorder(bt);
        default:
            break;
    }
    return 0;
}