我正在练习使用类和 vector 并将对象存储在 vector 中。在存储了一个基类对象和一个继承自它的类对象后,我的编译器返回了继承类对象不存在的错误。以下是我认为的重要部分:
继承自 Car 的 Car 类和 Sportscar 类
class Car
{
public:
Car();
void stop();
int get_speed() const;
void new_speed(int fspeed);
protected:
int speed;
};
class Sportscar : public Car
{
public:
Sportscar();
void turbo();
private:
bool hasTurbo;
};
将对象存储在 vector 车中:
vector<Car*> cars(2);
cars[0] = new Car();
cars[1] = new Sportscar();
访问 cars[0]
和 cars[1]
的情况,其中 cars[0]
访问正常,但是cars[1]
不是:
cars[1]->turbo();
cars[0]->new_speed(cars[0]->get_speed());
这是完整的代码,因为我一开始并不确定我要玩这个小型汽车游戏,所以代码有点乱:
#include <iostream>
#include <cstdlib>
#include <vector>
using namespace std;
class Car
{
public:
Car();
void stop();
int get_speed() const;
void new_speed(int fspeed);
protected:
int speed;
};
class Sportscar : public Car
{
public:
Sportscar();
void turbo();
private:
bool hasTurbo;
};
// Constructor for class Car
Car::Car()
{
speed = 1;
}
// Function to stop the car
void Car::stop()
{
speed = 0;
cout << "You stop the car.\n" << endl;
}
// Function to get current speed of the car
int Car::get_speed() const
{
return speed;
}
// Function to "accelerate" the car
void Car::new_speed(int fspeed)
{
int newspeed;
cout << "Speed up by how many mp/h? ";
cin >> newspeed;
speed = (fspeed + newspeed);
cout << "You speed up.\n" << endl;
}
// Sportscar constructor to set hasTurbo to 0 (no)
Sportscar::Sportscar()
// Not sure if this is necessary
: Car()
{
hasTurbo = 0;
}
// Function to designate if the car has turbo
void Sportscar::turbo()
{
hasTurbo = 1;
cout << "You have activated turbo and have greater acceleration.\n" << endl;
}
int main(void)
{
vector<Car*> cars(2);
cars[0] = new Car();
cars[1] = new Sportscar();
//Car drive;
//Sportscar drivefast;
char ans;
char sport;
// Asks user for input A, B, C, or Q until user chooses Q to quit
while(1)
{
cout << "Enter 'A' for current speed, 'B' to speed up, or 'C' to stop. 'Q' to quit." << endl;
cin >> ans;
// If users chooses A, calls get_speed() function and outputs current speed
if (ans == 'A')
{
cout << "Your current speed is " << cars[0]->get_speed() << " mp/h.\n" << endl;
}
// If user chooses B, calls new_speed() function to increase speed according to
// user's specifications
else if (ans == 'B')
{
// Asks user if they have turbo Y/N
cout << "Do you want to use turbo? Y/N: ";
cin >> sport;
// If user does have turbo, hasTurbo is set to 1 (yes) and function
// new_speed() is called
if (sport == 'Y')
{
cars[1]->turbo();
cars[0]->new_speed(cars[0]->get_speed());
}
// If user does not have turbo, hasTurbo stays at 0 (no) and function
// new_speed() is called
else if (sport == 'N')
{
cars[0]->new_speed(cars[0]->get_speed());
}
// If user answers other can Y or N, tells user input is incorrect
else
{
cout << "Incorrect input.\n" << endl;
}
}
// If user chooses C, calls stop() function and reduces car's speed to 0
else if (ans == 'C')
{
cars[0]->stop();
}
// If user chooses Q, program ends
else if (ans == 'Q')
{
exit(0);
}
// If user chooses other than A, B, C, or Q, tells user input is incorrect
else
{
cout << "Incorrect input.\n" << endl;
}
}
}
最后,这是我的编译器错误:
我应该注意,如果我删除访问 cars[1]
的行,程序会编译并运行良好。
最佳答案
您的 vector 被声明为 Car*
类型的 vector 。 Car
类型的对象没有 turbo
成员函数。您需要将指针转换为 Sportscar*
类型:
static_cast<Sportscar*>(cars[1])->turbo();
关于c++ - 将对象存储在 vector 中,编译器说元素不存在,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25736050/