数据结构 二叉树的建立及三种遍历方法

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
using namespace std;
typedef struct Binode{
    char data;
    struct Binode *lchild,*rchild;
}Binode,*Bitree;
void CreatTREE(Bitree &T)
{
    char ch;
    scanf("%c",&ch);
    if(ch==' ')
    {
        T=NULL;
    }
    else
    {
        T=(Bitree)malloc(sizeof(Binode));
        T->data=ch;
        CreatTREE(T->lchild);
        CreatTREE(T->rchild);
    }
    return;
}
void print_pre(Bitree &T)
{
    if((T!=NULL))
    {
        printf("%c ",T->data);
        print_pre(T->lchild);
        print_pre(T->rchild);
    }
    return;
}
void print_in(Bitree &T)
{
    if(T!=NULL)
    {
        print_in(T->lchild);
        printf("%c ",T->data);
        print_in(T->rchild);
    }
    return;
}
void print_after(Bitree &T)
{
    if(T!=NULL)
    {
        print_after(T->lchild);
        print_after(T->rchild);
        printf("%c ",T->data);
    }
}
int main()
{
    Bitree T;
    CreatTREE(T);
    print_pre(T);
    cout<<endl;
    print_in(T);
    cout<<endl;
    print_after(T);
    cout<<endl;
    return 0;
}