可以在类中使用 fstream 对象吗?

我有以下类定义...我想知道流对象。

#ifndef CLIENTLIST_H
#define CLIENTLIST_H
#include <string>
#include <vector>
#include <fstream>
using namespace std;
class ClientList
{
private:
// A structure for the list
struct ListNode
    {
        char gender;
        string name;
        string phone;
        int numInterests; // The number of interests for the client
        vector<string> interests; // list of interests
        string match;
        struct ListNode *next;  // To point to the next node
    }; 
    ListNode *head;            // List head pointer
    string name;
    void detach(string); // to unmatch the corresponding client
public:
    // Constructor
    ClientList();
    // Destructor
    ~ClientList();
    // Linked list operations
    void appendNode(char, string, string, int, vector<string>, string, fstream &);
    string interestCompare(vector<string>, string, fstream &);
    void unmatch(string, ClientList, fstream &);
    void printMatch(fstream &);
    void printFree(fstream &);
};
#endif

这是我尝试在类中使用 fstream 对象的第五种不同方式，但它们都不起作用，出现了各种错误。

这是我最近如何实现的功能示例

//**************************************************
// appendNode appends a node containing the        *
// value pased into num, to the end of the list.   *
//**************************************************
void ClientList::appendNode(char gen, string nm, string ph, int numIntr, 
                            vector<string> intr, string mch, fstream &dates)
{
    dates.open("dates.txt", ios::out | ios::out);
    ListNode *newNode;  // To point to a new node
    ListNode *nodePtr;  // To move through the list
    // Allocate a new node and store data in it.
    newNode = new ListNode;
    newNode->gender = gen;
    newNode->name = nm;
    newNode->phone = ph;
    newNode->numInterests = numIntr;
    newNode->interests = intr;
    newNode->match = mch;
    newNode->next = NULL;
    // If there are no nodes in the list
    // make newNode the first node.
    if (!head)
        head = newNode;
    // Otherwise, insert newNode at end.
    else  
    {
        // Initialize nodePtr to head of list.
        nodePtr = head;
        // Find the last node in the list.
        while (nodePtr->next)
            nodePtr = nodePtr->next;
        // Insert newNode as the last node.
        nodePtr->next = newNode;
    }
    dates << "nClient: " << newNode->gender << ", " << newNode->name << ", "
          << newNode->phone << ", " << newNode->numInterests << ", ";
    for (int index = 0; index < newNode->numInterests; index++)
        dates << newNode->interests[index] << ", ";
    dates << newNode->match << ".n";

    cout << "nnAPPENDEDnn";
    dates.close();
}

这是我如何从main（）调用它的一个例子

//append to file
    if (gender == tolower('m'))
    {       
        match = Female.interestCompare(interests, name, dates); // compare the vector of interests to the client interests
        // in the female list
        Male.appendNode(gender, name, phone, numInterests, interests, match, dates);        
    }

但就像我说的，这只是我的一次尝试，似乎无论我如何尝试让类打开文件并写入它，程序都会崩溃或执行一些不是后置条件的事情。

所以，我想知道是否可以在类中使用文件流。如果是这样，我需要保留什么才能做到这一点。

注意：我不一定在寻找特定的实现，我更想知道实现背后的"原因"。我想知道我需要记住什么，以便将来能够知道我在做什么。