错误:“root”未命名类型

对于节点的所有属性以及所有节点，我收到以下错误。

n-tree.h:35:2: error: ‘root’ does not name a type
  root->parent = NULL;
  ^

我想创建一个具有任意数量的子节点的树。我为树定义创建了一个头文件。

我首先将节点定义为结构。然后使用节点的定义，我创建了一个树。

我尝试了许多方法来解决此错误，例如，通过在 nTree 结构中定义 Node 结构，在其他常见实现中定义节点。

这里是 n-树。

#ifndef N_TREE
#define N_TREE
#include <cstdio>
struct Node
{
    Node* parent;
    Node* left_child;
    Node* right_sibling;
    double key;
};
struct nTree
{
// Nodes - attributes of the tree
Node* root;
Node* node1_1;
    Node* node1_1_1;
    Node* node1_1_2;
Node* node1_2;
    Node* node1_2_1;
    Node* node1_2_2;
    Node* node1_2_3;
Node* node1_3;
    Node* node1_3_1;

// Root level
root->parent = NULL;
root->left_child = node1_1;
root->right_sibling = NULL;
root->key = 1;
// Level 1_1
node1_1->parent = root;
node1_1->left_child = node1_1_1;
node1_1->right_sibling = node1_2;
node1_1->key = 2;
// Level 1_2
node1_2->parent = root;
node1_2->left_child = node1_2_1;
node1_2->right_sibling = node1_3;
node1_2->key = 3;
// Level 1_3
node1_3->parent = root;
node1_3->left_child = node1_3_1;
node1_3->right_sibling = NULL;
node1_3->key = 4;

// Level 1_1_1
node1_1_1->parent = node1_1;
node1_1_1->left_child = NULL;
node1_1_1->right_sibling = node1_1_2;
node1_1_1->key = 5;
 // Level 1_1_2
node1_1_2->parent = node1_1;
node1_1_2->left_child = NULL;
node1_1_2->right_sibling = NULL;
node1_1_2->key = 6;
// Level 1_2_1
node1_2_1->parent = node1_2;
node1_2_1->left_child = NULL;
node1_2_1->right_sibling = node1_2_2;
node1_2_1->key = 7;
// Level 1_2_2
node1_2_2->parent = node1_2;
node1_2_2->left_child = NULL;
node1_2_2->right_sibling = node1_2_3;
node1_2_2->key = 8;
// Level 1_2_3
node1_2_3->parent = node1_2;
node1_2_3->left_child = NULL;
node1_2_3->right_sibling = NULL;
node1_2_3->key = 9;
// Level 1_3_1
node1_3_1->parent = node1_3;
node1_3_1->left_child = NULL;
node1_3_1->right_sibling = NULL;
node1_3_1->key = 10;
};
#endif

这是 n-tree_implement.cpp

#include <cstdio>
#include "n-tree.h"
int main()
{
    nTree* tree = new nTree;
    printf("%dn", tree->root->key);
    delete tree;
}

包含上述头文件时，会为 nTree 中的所有节点提供以下错误。