二叉树遍历

#include<iostream>
#include<cstdio>
#include<string>
using namespace std;
struct treenode{
char data;
treenode* lchild;
treenode* rchild;
treenode(char c)
:data(c)
,lchild(NULL)
,rchild(NULL)
{}
};

treenode *build(string str,int & position)
{
    char c=str[position++];
    if(c=='#')
        return NULL;
   treenode *root=new treenode(c);
   root->lchild=build(str,position);
   root->rchild=build(str,position);
   return root;
}
void inorder(treenode *root)
{
    if(root==NULL)
    return ;
    inorder(root->lchild);
    printf("%c ",root->data);
    inorder(root->rchild);
    return;
}



int main()
{
    string str;
    while(cin>>str)
    {
        int position=0;
        treenode *root=build(str,position);
        inorder(root);
        printf("\n");
    }

    return 0;
}