问为什么C++不允许我在类中使用字符串作为数据成员？

EN

#ifndef CLASSESS_H
#define CLASSESS_H

class PalindromeCheck
{
private:
    string strToCheck;
    string copy;

public:
    PalindromeCheck(string testSubject) : strToCheck(testSubject) {} //Constructor

    void Check()
    {
        copy = strToCheck; //Copy strToCheck into copy so that once strToCheck has been reversed, it has something to be checked against.
        reverse(strToCheck.begin(), strToCheck.end());  //Reverse the string so that it can be checked to see if it is a palindrome.

        if (strToCheck == copy) 
        {
            cout << "The string is a palindrome" << endl;
            return;
        }
        else 
        {
            cout << "The string is not a palindrome" << endl;
            return;
        }
    }
};

#endif

#include <iostream>
#include <string>
#include <algorithm>
#include "Classes.h"
using namespace std;

int main()
{
    PalindromeCheck firstCheck("ATOYOTA");

    firstCheck.Check();

    return 0;
}