如何从一个函数传递一个struct并将其从头文件返回到main [英] How to pass and return a struct from a function to main from header file

问题描述

您好，我需要一些帮助，我正在尝试从我的头文件调用一个函数到我的main，这个函数返回一个结构。



这里的问题是我没有得到如何调用一个从它返回结构的函数，我尝试了一些东西，但没有任何工作。



输出

Hello, I need some help with this, I'm trying to call a function from my header file to my main, this function return a structure.

The problem here is that I don't get how to call a function that returns a structure from it, I have tried some things but nothing has worked.

Output

error: request for member 'Insert' in 'root', which is of pointer type 'TREE::tree*' (maybe you meant to use '->' ?)
   root = root.Insert(root, 9);

error: request for member 'Print' in 'root', which is of pointer type 'TREE::tree*' (maybe you meant to use '->' ?)
  root.Print(root);

头文件

The header file

#ifndef _LibArb_H_
#define _LibArb_H_

struct Node{
	
	int val;
	Node *left, *right;
	
};

using namespace std;
namespace TREE
{

class tree
{

	private:
	
		Node *node;
		
	public:
	
		tree();
		~tree();
		
Node* Insert(Node *node, int val) // Returns a struct
{
	if(node == NULL) // If no nodes then create a new one
	{
		node = new Node;
		node->val = val;
		node->right = node->left = NULL;
	}	
	
	else if(node->val > val)
		node->left = Insert(node->left, val); // Insert value on the left node
	else
		node->right = Insert(node->right, val); // Insert value on the right node
	
	return node; // Return the value of node
}

void Print(Node *node)
{
	
	if (node)
	{
		cout << "Val: " << node->val << endl;
		cout << "Left: " << node->left << endl;
		cout << "Right: " << node->right << endl;
		Print(node->left);
		Print(node->right);
	}
}
};
}

# endif // _LibArb_H_

#include <iostream>
#include "LibArb.h"

using namespace std;
using namespace TREE; // From the header file

int main()
{

	tree *root = NULL; // Create new root from the class tree of the header file
	
		root = root.Insert(root, 9); // New node with the number 9 on it
	
	root.Print(root); // Print all the nodes from the tree

	
	return 0;
}

我的尝试：



root = root-> Insert（root，9）;失败

插入（root，9）;失败

What I have tried:

root = root->Insert(root, 9); Fail
Insert(root, 9); Fail

推荐答案

tree *root = NULL; // Create new root from the class tree of the header file

root = root.Insert(root, 9); // New node with the number 9 on it

第一个语句创建一个指针并将其设置为NULL，因此它不指向任何内容。然后尝试在NULL指针上调用 Insert 方法，该方法将始终失败。你需要初始化 root ，然后你可以使用它，但是 - > 引用，而不是dot;因此：

The first statement creates a pointer and sets it to NULL, so it does not point to anything. You then try and call the Insert method on a NULL pointer which will always fail. You need to initialise root and then you can use it, but by -> reference, not dot; thus:

tree *root = new tree(); // Create new tree pointer
// and as root is a pointer we need to use the -> reference type
root = root->Insert(root, 9); // New node with the number 9 on it

但是，正如您的代码所示，现在将覆盖根指针，因此它将丢失。我怀疑Insert方法需要一些工作，或者树类中的节点变量应该公开。

However, as your code stands, this will now overwrite the root pointer so it will be lost. I suspect the Insert method needs some work, or the node variable in the tree class should be made public.

tree *root = new tree(); // Create new tree pointer
// and as root is a pointer we need to use the -> reference type
root->node = root->Insert(root, 9); // New node with the number 9 on it

您还应该从头文件中删除类的实现，只留下声明。

You should also remove the implementation of your classes from the header file and leave just the declarations.

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