帮我看看我的代码有什么问题：#include<iostream> #include<string> using namespace std; class Vehicle { protected: string no; //编号 public: Vehicle(string no) { this->no = no; } virtual void display() = 0; //应收费用 }; class Car :public Vehicle { public: int num; float weight; Car(string no, int num, float weight) :Vehicle(no) { this->num = num; this->weight = weight; } void display() { cout << no << " " << num * 8 + weight + 2 << endl; } }; class Bus：public Vehicle { public: int num; Bus(string no, int num) :Vehicle(no) { this->num = num; } void display() { cout << no << " " << num*30 << endl; } }; class Truck ：public Vehicle { public: float weight; Truck(string no, int weight) :Vehicle(no) { this->weight = weight; } void display() { cout << no << " " << weight* 5 << endl; } }; int main() { int t; cin >> t; int type; string no; while (t--) { if (type == 1){ Car car; Vehicle* pv = &car; } else if (type == 2) { Truck truck; Vehicle* pv = &truck; } else if (type == 3) { Bus bus; Vehicle* pv = &bus; } pv.display(); } return 0; }

你的代码存在几个问题：

1. 在主函数里，你没有读取每个车辆的类型和编号。你需要添加以下代码：

cin >> type >> no;

在读取完车辆类型和编号后，你需要判断车辆类型，然后创建相应的对象，并将指针指向该对象。

2. 在创建车辆对象时，你需要传入相应的参数。例如，对于Car，你需要传入num和weight。

3. 在创建车辆对象时，你需要使用new运算符。例如，对于Car，你需要使用以下代码：

Vehicle* pv = new Car(no, num, weight);

4. 在主函数里，你需要调用display函数来输出每个车辆的应收费用。你需要将指针解引用后再调用display函数。例如，对于Car，你需要使用以下代码：

pv->display();

修改后的代码如下所示：

相关问题

帮我看看我修改后的代码有什么问题：#include<iostream> #include<string> using namespace std; class Vehicle { protected: string no; //编号 public: Vehicle(string no) { this->no = no; } virtual void display() = 0; //应收费用 }; class Car :public Vehicle { public: int num; float weight; Car(string no, int num, float weight) :Vehicle(no) { this->num = num; this->weight = weight; } void display() { cout << no << " " << num * 8 + weight + 2 << endl; } }; class Bus:public Vehicle { public: int num; Bus(string no, int num) :Vehicle(no) { this->num = num; } void display() { cout << no << " " << num*30 << endl; } }; class Truck :public Vehicle { public: float weight; Truck(string no, int weight) :Vehicle(no) { this->weight = weight; } void display() { cout << no << " " << weight* 5 << endl; } }; int main() { int t; cin >> t; int type; string no; int num; float weight; while (t--) { cin >> type >> no; if (type == 1){ cin >> num >> weight; Vehicle* pv = new Car(no,num,weight);; } else if (type == 2) { cin >> weight; Vehicle* pv = new Truck (no, weight);; } else if (type == 3) { cin >> num ; Vehicle* pv =new Bus(no,num);; } pv->display(); } return 0; }

在代码中，对象指针 `pv` 在条件语句中被定义并初始化，但是在条件语句块之外被使用。这会导致编译错误，因为在使用它时，它可能没有被初始化。要解决这个问题，可以将对象指针的定义移动到条件语句块之前。修改后的代码如下所示：

#include<iostream>
#include<string>
using namespace std;

class Vehicle {
protected:
    string no; //编号
public:
    Vehicle(string no)
    {
        this->no = no;
    }
    virtual void display() = 0; //应收费用
};

class Car :public Vehicle {
public:
    int num;
    float weight;
    Car(string no, int num, float weight) :Vehicle(no)
    {
        this->num = num;
        this->weight = weight;
    }
    void display()
    {
        cout << no << " " << num * 8 + weight + 2 << endl;
    }
};

class Bus :public Vehicle {
public:
    int num;
    Bus(string no, int num) :Vehicle(no)
    {
        this->num = num;
    }
    void display()
    {
        cout << no << " " << num * 30 << endl;
    }
};

class Truck :public Vehicle {
public:
    float weight;
    Truck(string no, float weight) :Vehicle(no)
    {
        this->weight = weight;
    }
    void display()
    {
        cout << no << " " << weight * 5 << endl;
    }
};

int main() {
    int t;
    cin >> t;
    int type;
    string no;
    int num;
    float weight;
    while (t--)
    {
        cin >> type >> no;
        Vehicle* pv;
        if (type == 1) {
            cin >> num >> weight;
            pv = new Car(no, num, weight);
        }
        else if (type == 2) {
            cin >> weight;
            pv = new Truck(no, weight);
        }
        else if (type == 3) {
            cin >> num;
            pv = new Bus(no, num);
        }
        pv->display();
    }
    return 0;
}

另外，还有一个小错误：在 `Truck` 类中的构造函数中，`weight` 参数应该为 `float` 类型而不是 `int` 类型。已经在上面的代码中进行了修正。

优化这段代码并消除bug:#include<iostream> #include<string> using namespace std; class Vehicle{ protected: string name; string color; public: Vehicle(string n,string c):name(n),color(c){}; virtual void display(); }; class Car : public Vehicle{ private: int pas; public: Car(string n,string c,int p):Vehicle(n,c),pas(p){}; void display(){ cout << name << " " << color << " " << pas << endl; }; }; class Truck : public Vehicle{ private: double weight; public: Truck(string n,string c,double d):Vehicle(n,c),weight(d){}; void display(){ cout << name << " " << color << " " << weight << endl; }; }; int main() { Vehicle *p; char type; char name[110],color[110]; int pas; double cap; while(cin>>type) { cin>>name>>color; if(type == 'C') { cin>>pas; Car car(name,color,pas); p = &car; p->display(); } else if(type == 'T') { cin>>cap; Truck truck(name,color,cap); p = &truck; p->display(); } } return 0; }

优化后的代码如下，主要是将类的成员变量改为指针类型，避免在栈上分配内存导致指针失效：

#include<iostream>
#include<string>
using namespace std;

class Vehicle{
protected:
    string name;
    string color;
public:
    Vehicle(string n, string c): name(n), color(c){};
    virtual void display() = 0;
    virtual ~Vehicle(){} // 添加虚析构函数
};

class Car : public Vehicle{
private:
    int *pas; // 改为指针类型
public:
    Car(string n, string c, int p): Vehicle(n, c){
        pas = new int(p); // 动态分配内存
    };
    void display(){
        cout << name << " " << color << " " << *pas << endl;
    };
    ~Car(){ // 添加析构函数，释放内存
        delete pas;
    }
};

class Truck : public Vehicle{
private:
    double *weight; // 改为指针类型
public:
    Truck(string n, string c, double d): Vehicle(n, c){
        weight = new double(d); // 动态分配内存
    };
    void display(){
        cout << name << " " << color << " " << *weight << endl;
    };
    ~Truck(){ // 添加析构函数，释放内存
        delete weight;
    }
};

int main() {
    Vehicle *p;
    char type;
    char name[110], color[110];
    int pas;
    double cap;
    while(cin>>type) {
        cin>>name>>color;
        if(type == 'C') {
            cin>>pas;
            p = new Car(name, color, pas); // 动态分配内存
            p->display();
            delete p; // 释放内存
        }
        else if(type == 'T') {
            cin>>cap;
            p = new Truck(name, color, cap); // 动态分配内存
            p->display();
            delete p; // 释放内存
        }
    }
    return 0;
}

此外，还需要添加虚析构函数，在子类析构时能够自动调用父类析构函数，释放父类的内存。并且在动态分配内存后需要在适当的时候释放内存，避免内存泄漏。