Question

因此，我正在为Uni中的作业创建此作品。

它必须使用以'Vehicle'作为主类的类结构，以及从中继承一些函数的两个类; 'Car'和'Lorry'。

所以我已经成功创建了我的类结构（我认为）但我需要为此创建一个基本的UI，因为它认为它是一个控制台应用程序，我只是使用开关创建一个基本菜单。

然而，在我的“getDetails”部分中，它只是抓住'Vehicle :: getDetails'，它还应该获得'Car / lorry :: getdetails'，以及车辆细节。

任何想法可能导致什么？

首先在这里发帖，很抱歉，如果我的帖子不好:(。

谢谢！

#include <iostream> 
#include <string>
#include <fstream>

using namespace std;


class vehicle {    

public:     

string manufacturer;
int year;
string regnum;

void getDetails() { 

    cout << "Please enter the details for your vehicle"<< endl;
    cout << "Please enter the manufacturer of your vehicle: "<< endl;
    cin >> manufacturer;
    cout << "Please enter the year of your vehicle's manufacture: "<< endl;
    cin >> year;
    cout << "Please enter your vehicle's registration number:  "<< endl;
    cin >> regnum;

}


void printDetails() {

    cout << "Your vehicle's details are as follows: " << endl;
    cout << "Your Vehicle's manufacturer is " << manufacturer << endl;
    cout << "Your Vehicle's year of manufacture is " << year << endl;
    cout << "Your Vehicle's registration number is " << regnum << endl;
}

void saveDetails() { 

    ofstream vehiclefile;
    vehiclefile.open ("vehicle.txt");
    vehiclefile << "***Your Vehicle's Details***" << endl;
    vehiclefile << "Manufacturer:" << manufacturer << endl;
    vehiclefile << "Year of Manufacture:" << year << endl;
    vehiclefile << "Registration Number: " << regnum << endl;
    vehiclefile.close();
}

void openVehicleDetails() { 

}
};


class car : public vehicle{

public:

int numpassengers;
string cartype;

void getDetails() { 

    vehicle::getDetails();

    cout << "Please enter the number of maximum passengers your car can hold: "<< endl;
    cin >> numpassengers;
    cout << "Please enter the car body type: "<< endl;
    cin >> cartype;
    cout << "Thank your for your details"<< endl;
}

void printDetails() {

    vehicle::printDetails();

    cout << "Your car's maximum passengers is: " << numpassengers << endl;
    cout << "The body type of your car is: " << cartype << endl;
}

void saveDetails() { 

    vehicle::saveDetails();

    ofstream vehiclefile;
    vehiclefile.open ("vehicle.txt");
    vehiclefile << "Car or Lorry: Car" << endl;
    vehiclefile << "Number of passengers: " << numpassengers << endl;
    vehiclefile << "Type of car: " << cartype << endl;
    vehiclefile.close();
}
};


class lorry : public vehicle{

public:

double tonnage;
string bodtype;

void getDetails() {

    vehicle::getDetails();

    cout << "Please enter the gross weight of your Lorry: "<< endl;
    cin >> tonnage;
    cout << "Please enter the body type of your Lorry: "<< endl;
    cin >> bodtype;
    cout << "Thank your for your details"<< endl;
}

void printDetails() {

    vehicle::printDetails();

    cout << "Your lorry's details are as follows: " << endl;
    cout << "Your lorry's maximum weight is: " << tonnage << endl;
    cout << "The body type of your lorry is: " << bodtype << endl;
}

void saveDetails() { 

    vehicle::saveDetails();

    ofstream vehiclefile;
    vehiclefile.open ("vehicle.txt");
    vehiclefile << "Car or Lorry: Lorry" << endl;
    vehiclefile << "Maximum weight: " << tonnage << endl;
    vehiclefile << "Body type: " << bodtype << endl;
    vehiclefile.close();
}

};


int main () {

int flag = 0;
char choice;
int ifchoice;

vehicle*v;


while (flag == 0){

    cout << "***Main Menu***" << endl;      //Menu to allow ease of access within the program.
    cout << "Select by letter:" << endl;     
    cout << "1 - Add new entry" << endl;
    cout << "2 - Show entry" << endl;
    cout << "3 - Save entry" << endl;
    cout << "4 - Open saved document" << endl;
    cout << "5 - Delete entry" << endl;
    cin >> choice;          

    switch(choice) {       

    case '1':

        cout << "Is your vehicle a Car or a Lorry? " << endl;
        cout << "Press '1' for Car " << endl;
        cout << "Press '2' for Lorry " << endl;
        cin >> ifchoice;

            if (ifchoice == 1)
            {
                v = new car();
            }
            if (ifchoice == 2)
            {
                v = new lorry();
            }

            v->getDetails();

        break;

    case '2':

        v -> printDetails();

        break;

    case '3': 

        v -> saveDetails();

        break;




   }    

}
}

Answer 1

练习的重点是在基础void getDetails()课程中制作virtual方法 vehicle 。

（我也在virtual类中定义了一个vehicle析构函数，作为良好的编码实践。）

class vehicle {    
public:         
    string manufacturer;
    int year;
    string regnum;

    // Make this virtual
    virtual void getDetails() { 
         ...

在派生类中，您可能也想使用the new C++11 override specifier。

Answer 2

在c ++中，如果希望某个函数可以被派生类覆盖，则将其标记为virtual，即：

class vehicle {
    ...
    virtual void getDetails()
    {
        ...
    }
    ...
}

类继承问题c ++

2 个答案: