#ifndef 不允许我的文件查看 header (C++) 中的内容

Question

So I created a Binary tree class and I want to separate the class definition from its member function definition by putting the class def in the.h file and the function definitions in the.cpp file. 然后我会将.h 文件包含到.cpp 文件中。 现在我得到了所有的工作，它工作正常。 问题是当我想输入包括警卫在内的名字时。 因为我需要在成员 function.cpp 文件和另一个使用二叉树 class 的.cpp 文件中包含.h 文件，所以我必须包含这些保护。 但是由于某种原因，一旦我将它们都包含在内，这两个.cpp 文件似乎就不会“看到” header 文件的内容。 我是使用 ifndef 的新手，所以我很确定我做错了什么。 谢谢你

这是名为 node.h 的 header 文件：

#ifndef NODE_H
#define NODE_H

#include <iostream>
#include <string>
#include <vector>
#include <stdbool.h>
using std::cout;
using std::endl;
typedef std::vector<std::string> vectorString;

class BST  
{ 
    vectorString data; 
    BST *left, *right; 
  
public: 
    // Default constructor. 
    BST(); 
  
    // Parameterized constructor. 
    BST(std::string); 
  
    // Insert function. 
    BST* Insert(BST*, std::string); 
  
    // Inorder traversal. 
    void Inorder(BST*); 

    // PreOrder Traversal.
    void PreOrder(BST*);

    // PostOrder Traversal
    void PostOrder(BST*);

    // string slicer
    std::string strSlice(std::string);

    // boolean isDuplicate
    bool isDuplicate(std::string, vectorString);

    // print vector
    void printVector(vectorString);
};

#endif

这是名为 node.cpp 的成员定义文件

#include <iostream>
//#include "node.h" 
#include <string>
#include <vector>
using std::cout;
using std::endl;
  
  
// Default Constructor definition. 
BST ::BST()
    : data(0) 
    , left(NULL) 
    , right(NULL) 
{ 
} 
  
// Parameterized Constructor definition. 
BST ::BST(std::string value) 
{ 
    if(data.empty()){
        data.push_back(strSlice(value));
    }
        data.push_back(value); 
    
    left = right = NULL; 
} 
  
// String slicing function definition
std::string BST ::strSlice(std::string word){
    std::string word2 = "";
    word2 += word[0];
    word2 += word[1];
    return word2;
}


// print vector function definition
void BST ::printVector(std::vector<std::string> dataVector){
    for(int i = 0; i < dataVector.size(); i ++){
        cout << dataVector.at(i) << " ";
    }
}

// Insert function definition. 
BST* BST ::Insert(BST* root, std::string value) 
{ 
    if (!root)  
    { 
        // Insert the first node, if root is NULL. 

        return new BST(value); 
    } 
  
    // Insert data. 
    if (strSlice(value).compare(root->data.at(0)) > 0)  
    { 
        // Insert right node data, if the 'value' 
        // to be inserted is greater than 'root' node data. 
        cout << value << " is being put in the right node " << value << " > " << root->data.at(0) << endl;
        // Process right nodes. 
        root->right = Insert(root->right, value); 
        
    } else if (strSlice(value).compare(root->data.at(0)) == 0) {

        cout << value << " is being put in the same node " << value << " = " << root->data.at(0)  << endl;
        root->data.push_back(value);
    }
    else 
    { 
        // Insert left node data, if the 'value' 
        // to be inserted is greater than 'root' node data. 
        cout << value << " is being put in the left node " << value << " < " << root->data.at(0) << endl;
        // Process left nodes. 
        root->left = Insert(root->left, value); 
    } 
  
    // Return 'root' node, after insertion. 
    // cout << "after insert root is " << root << endl;
    return root; 
} 
  
// Inorder traversal function. 
// This gives data in sorted order. 
void BST ::Inorder(BST* root) 
{ 
    if (!root) { 
        return; 
    } 
    Inorder(root->left); 
    printVector(root->data);
    cout << endl; 
    Inorder(root->right); 
}
void BST::PreOrder(BST* root){
    if(!root){
        return;
    }
    root->printVector(root->data);
    cout << endl;
    PreOrder(root->left);
    PreOrder(root->right);
} 
void BST::PostOrder(BST* root){
    if(!root){
        return;
    }
    PostOrder(root->left);
    PostOrder(root->right);
    root->printVector(root->data);
    cout << endl;
} 

错误：

C:\Users\14jjo\C++ Projects\Project 0\node.cpp:12:1: error: 'BST' does not name a type
 BST ::BST()
 ^~~
C:\Users\14jjo\C++ Projects\Project 0\node.cpp:20:1: error: 'BST' does not name a type
 BST ::BST(std::string value)
 ^~~

这是试图实现名为 P0.cpp 的二叉树 class 的 class：

#include <iostream>
//#include "tree.h"
#include "cleanString.h"
#include "node.h"
#include <fstream>
#include <string>
using std::cout;

using std::endl;

int main(int argc, char** argv) {
    std::ifstream fileRead;
    std::string word;

    fileRead.open(argv[1]);
    if(!fileRead){
        cout << "this is not a file\n";
    } else { cout << "this is a file\n"; }

    fileRead >> word;
    word = cleanString(word);
    BST tree, *root = nullptr;
    root = tree.Insert(root, word);

    while (fileRead >> word) {
        word = cleanString(word);
        tree.Insert(root, word);
    }

    tree.Inorder(root);

    fileRead.close();


    return 0;
}

错误：

C:/Users/14jjo/C++ Projects/Project 0/P0.cpp:22: undefined reference to `BST::BST()'
C:/Users/14jjo/C++ Projects/Project 0/P0.cpp:23: undefined reference to `BST::Insert(BST*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)'

Answer 1

只需#include "node.h" 并确保编译所有 cpp 文件