'string' 不命名类型；您指的是 'stdin' 吗？

Question

我正在尝试编译一个引用我的“CardCreator.h”文件的 main.cpp 文件。当我尝试编译“main.cpp”文件时，它会抛出错误

undefined reference to `CardCreator::getCardHealth()' collect2.exe: error: ld returned 1 exit status

我的代码看起来像：

main.cpp

#include <iostream>
#include <string>
#include <fstream>
#include "CardCreator.h"




void myFunction() {
    std::string name = "function name";
    std::cout << name << std::endl;

}

int main(int argc, char** argv){
    CardCreator machine;
    machine.getCardHealth();
    std::cout << "hello world" << std::endl;    myFunction();

}

CardCreator.cpp - 应该注意函数 getCardName() 包含一些不做太多的代码。

#include <iostream>
// #include <string>
#include <fstream>
using namespace std;
#include "CardCreator.h"

bool CardCreator::fileCheck()
{
    if (fopen("card.json", "r"))
    {
        cout << "found" << endl;
        return true;
    }
    else
    {
        cout << "Not found" << endl;
        // ofstream MyFile("card.json", ios_base::app);
        // MyFile.close();
        return false;
    }
}

// methods go here

std::string CardCreator::getCardName(){
    cout << "enter card name: " << endl;
    // getline(cin,name);
    // // cin >> name;
    // cin.getline(name, 20) >> ws;
    // cout << "the card is called: " << name << endl;
    // this fix came from [https://stackoverflow.com/questions/26071275/c-while-loop-and-getline-issue]
    // must clear the buffer for the while loop to allow input(break the loop)
    // getline(cin, name);
    // cin.ignore(256,'\n');
    bool validInput = false;
    while (!validInput)
    {
        cout << "enter card name: " << endl;
        getline(cin >> ws, name);
        if (name[0] != '\0')
        {
            cout << "The name is: " << name << endl;
            validInput = true;
        }
        else
        {
            cout << "Invalid input. Please try again." << endl;
        }
    }
    return name;
}
//file continues

int main() {}

CardCreator.h

#ifndef CARDCREATOR_H
#define CARDCREATOR_H
#include <string>

class CardCreator  {


private:
    bool isCreature;
    bool isCastable;

public:
    // change to char
    std::string name;
    int hp;
    int atk;
    int mana;
    int cards_to_create;



    bool fileCheck();

    std::string getCardName();

    int getCardAtk();

    int getCardHealth();

    int getCardMana();

    int CardsToCreate();

    void saveCard(std::string cardName,int cardatk, int cardhp, int cardmana);

};

#endif

我不确定为什么会出现错误。