c++ - 类之间的信息丢失

Question

对于我在 C++ 中的一个编程类(class)，我们需要设计一个配对代理，并且在我创建一个新客户端后，它会以某种方式将其添加到运营商的 += 到客户端数组中，然后在 MENU 类中数据库丢失了客户端，我可以好像没找到原因。

添加客户端运算符(operator)

MatchmakingAgency& MatchmakingAgency:: operator+=( Client& c1)
{   
    if (m_clients)//Client** m_clients; 
    {
        m_length++;
        Client** newArr = new Client * [m_length];
        if (!newArr)
        {
            cout << " Memory allocation failed!" << endl;
            return *this;
        }
        //copy old array to new
        for (int i = 0; i < m_length - 1; i++)
        {
            newArr[i] = m_clients[i];
        }
        newArr[m_length - 1] = &c1;
        //delete allocation
        delete[] m_clients;
        m_clients = newArr;
        delete[] newArr;
    }
    else //m_clients is empty
    {
        m_length = 1;
        m_clients = new Client * [1];

        if (!m_clients)
        {
            cout << " Memory allocation failed!" << endl;
            return *this;
        }
        m_clients[0]= &c1;
    }
    return *this;
}

**菜单添加客户//来自用户的所有客户信息**

{

    char temp[20];  //pointer to dynamically allocated data
    char gender;
    int age;
    int num_of_hobbies;
    cout << " enter ID number ->  ";
    cin >> temp;
    String id = temp;
    cout << "\n enter name ->  " ;
    cin.ignore();
    cin.getline(temp,20);
    String name = temp;
    cout << "\n enter gender F/M->  " ;
    cin >> gender;
    cout << "\n enter age ->  " ;
    cin >> age;
    if (age < 18)
    {
        cout << " Not in appropriate age!  " << endl;
        return;
    }
    cout << "\n enter number of hobbies ->  " ;
    cin >> num_of_hobbies;
    cout << '\n';
    char** hobby = new char* [num_of_hobbies];
    if (!hobby)
    {
        cout << "memory allocation failed!" << endl;//show message
        return;//go back
    }
    cout << "\n enter hobbies ->  " << endl;
    cin.ignore();
    for (int i = 0; i < num_of_hobbies; i++)
    {
        cin.getline(temp,20);
        hobby[i] = new char[(int)(strlen(temp)) + 1];
        for(int j=0;j<=(int)strlen(temp);j++)
        hobby[i][j] = temp[j];
    }


        Client cl1(id, name, gender, age, num_of_hobbies, hobby);
        m_data_base.operator+=(cl1);
    **//right here the m_data_base lost client info**
    for (int i = 0; i < num_of_hobbies; i++)
        delete[] hobby[i];
    delete[] hobby;
}

Answer 1

您已将客户端指针复制到 newArr，添加新的，然后在将 m_clients 设置为 newArr 指针后，您通过删除 newArr 指针删除刚刚复制的所有内容。

    delete[] m_clients;
    m_clients = newArr;
    delete[] newArr;