struct BTreeNode{
                  char data;
                  struct BTreeNode *lchild;
                  struct BTreeNode *rchild;
                 }
void R_Inorder(NODE *t)
{  if (root!=NULL)
      {
         R_Inorder(t->lchild);/*这一部分函数递推倒t->lchild为空时结束,回溯的值是什么？？*/
         printf("%c",t->data);
         R_Inorder(t->rchild);
       }
}
这是一个递归的2叉树中序遍历 问题已经注上望高手指点 谢谢

不返回值，当函数参数不为空时，打印节点，为空时，什么都不做。

我想問一下. if (root!=NULL)
和 printf("%c",t->data);
這兩個語句是什麽意思.??

理解了 谢谢指点啊

二叉树的中序遍历。如根节点不为空，则访问该根节点的左子树，如左子树为空则访问根节点（此处为打印根节点的数据域值），后在访问右子树。这是函数的嵌套问题。

//二叉树的应用：二叉树的构造、遍历。
//2008.04.12
#include<stdio.h>
#include<iostream>
using namespace std;
struct binaryTreeNode
{
    char data;
    struct binaryTreeNode *lefttree,*righttree;
};
typedef struct binaryTreeNode BinaryTree;
char ch=' ';
void CreateTree(BinaryTree *&tree)
{  
    if(ch!='\n')
    { ch=getchar();
       if(ch=='\n')
           return;
       if(ch=='.')
         tree=NULL;
        else
        {
           tree=new BinaryTree;           
           tree->data=ch;
           tree->lefttree=NULL;
           tree->righttree=NULL;
           CreateTree(tree->lefttree);
           CreateTree(tree->righttree);
        }
    }
    else return;
}

void PreOrder(BinaryTree *tree)
{
    if(tree!=NULL)
    {   
        putchar(tree->data);
        PreOrder(tree->lefttree);
        PreOrder(tree->righttree);
    }
}

void InOrder(BinaryTree *tree)
{
    if(tree!=NULL)
    {   
        InOrder(tree->lefttree);
        putchar(tree->data);
        InOrder(tree->righttree);
    }
}

void PostOrder(BinaryTree *tree)
{
    if(tree!=NULL)
    {   
        PostOrder(tree->lefttree);        
        PostOrder(tree->righttree);
        putchar(tree->data);
    }
}

int main()
{
    BinaryTree *t=NULL;
    cout<<"（输入时以前序和完全二叉树的形式，空结点用'.'代替，遇到叶子结点时加输两个'.'）"<<endl;
    cout<<"请输入一串字符串："<<endl;
    CreateTree(t);
    cout<<"按前序遍历："<<endl;
    PreOrder(t);
    cout<<endl;
    cout<<"按中序遍历："<<endl;
    InOrder(t);
    cout<<endl;
    cout<<"按后序遍历："<<endl;
    PostOrder(t);
    cout<<endl;
    return 0;
}

这几天做的实验