B+ 树插入和搜索

Question

我正在尝试使用 b+tree 实现文件中信息的插入和搜索，同时这样做我得到一个未定义引用的错误

我已经对原始代码进行了更改，其链接在下面仅给出了 main.cpp 和头文件已更改

main.cpp

#include <iostream>
#include <vector>
//#include <algorithm>
#include <fstream>
#include <string>
//#include <filesystem>
#include "BPTree.h"

void insertionMethod(BPTree** bPTree) {
    int rollNo;
    int age, marks;
    std::string name;

    std::cout << "Please provide the rollNo: ";
    std::cin >> rollNo;

    std::cout << "\nWhat's the Name, Age and Marks acquired?: ";
   std::cin >> name >> age >> marks;

    std::string fileName = "DBFiles/";
     fileName += std::to_string(rollNo) + ".txt";
    FILE* filePtr = fopen(fileName.c_str(), "w");
    std::string userTuple = name + " " + std::to_string(age) + " " + std::to_string(marks) + "\n";
    fprintf(filePtr, userTuple.c_str());
    //fclose(filePtr);

    (*bPTree)->insert(rollNo, filePtr);
    fclose(filePtr);
    std::cout << "Insertion of roll No: " << rollNo << " Successful"<<std::endl;
}

void searchMethod(BPTree* bPTree) {
    int rollNo;
    std::cout << "What's the RollNo to Search? ";
    std::cin >> rollNo;

    bPTree->search(rollNo);
}
int main() {
  
    bool flag = true;
    int option;

    int maxChildInt = 4, maxNodeLeaf = 3;
    std::cout << "Please provide the value to limit maximum child Internal Nodes can have: ";
    std::cin >> maxChildInt;
    std::cout << "\nAnd Now Limit the value to limit maximum Nodes Leaf Nodes can have: ";
    std::cin >> maxNodeLeaf;

    BPTree* bPTree = new BPTree(maxChildInt, maxNodeLeaf);
    std::cout<<bPTree->getMaxLeafNodeLimit()<<std::endl;
    do {
        std::cout << "\nPlease provide the queries with respective keys : " << std::endl;
        std::cout << "\tPress 1: Insertion \n\tPress 2: Search<< std::endl;
        std::cin >> option;

        switch (option) {
            case 1:
                insertionMethod(&bPTree);
                break;
            case 2:
                searchMethod(bPTree);
                break;
            default:
                flag = false;
                break;
        }
    }while (flag);

    return 0;
}

BPTree.h

#include <iostream>
#include <vector>
#include <algorithm>
#include <fstream>
#include <string>

#ifndef NODE_H
#define NODE_H
class Node {
   public:
    bool isLeaf;
    std::vector<int> keys;
  
    Node* ptr2next;              
    union ptr {                    
        std::vector<Node*> ptr2Tree;  //Array of pointers to Children sub-trees for intermediate Nodes
        std::vector<FILE*> dataPtr;   // Data-Pointer for the leaf node

        ptr();   // To remove the error !?
        ~ptr();  // To remove the error !?
    } ptr2TreeOrData;

    friend class BPTree;  // to access private members of the Node and hold the encapsulation concept
   public:
    Node(){
        this->isLeaf = false;
        this->ptr2next = NULL;
    }
};



class BPTree {
   private:
    int maxIntChildLimit;                                   //Limiting  #of children for internal Nodes!
    int maxLeafNodeLimit;                                   // Limiting #of nodes for leaf Nodes!!!
     Node* root;  Node* pparent = NULL;                                           //Pointer to the B+ Tree root
    void insertInternal(int x, Node** cursor, Node** child);  //Insert x from child in cursor(parent)
  Node** findParent(Node* cursor, Node* child){
       if (cursor->isLeaf || cursor->ptr2TreeOrData.ptr2Tree[0]->isLeaf)
        return NULL;

    for (int i = 0; i < cursor->ptr2TreeOrData.ptr2Tree.size(); i++) {
        if (cursor->ptr2TreeOrData.ptr2Tree[i] == child) {
            pparent = cursor;
        } else {
            Node* tmpCursor = cursor->ptr2TreeOrData.ptr2Tree[i];
            findParent(tmpCursor, child);
        }
    }

    return &pparent;
  }


   public:
    BPTree();
    BPTree(int degreeInternal, int degreeLeaf){
        this->maxIntChildLimit = degreeInternal;
    this->maxLeafNodeLimit = degreeLeaf;
    this->root = NULL;
    }

    int getMaxIntChildLimit();
    int getMaxLeafNodeLimit() 
    {
        return maxLeafNodeLimit;
    }
    void search(int key);
    void insert(int key, FILE* filePtr);
   
};
#endif

Search 和Insert 代码

我得到的错误是

C:\Users\admin\AppData\Local\Temp\cctqZ0YA.o:insert.cpp:(.text$_ZN4NodeC1Ev[__ZN4NodeC1Ev]+0x20): undefined reference to `Node::ptr::ptr()'
collect2.exe: error: ld returned 1 exit status

我不太确定 Node::ptr::ptr() 是什么，有人可以帮忙

Answer 1

删除那些已声明但未定义的构造函数和析构函数后得到的错误消息指向实际问题。为什么联合可能需要构造函数和析构函数在别处有更好的解释，例如here 和 here。

您可以通过提供一个简单的空实现来编译您的代码。

ptr() {};
~ptr() {};