#include <iostream> #include <string> using namespace std; class Person {static int f; protected: string name_; public: Person(){cout<<"A person without name is created."<<endl;f=0;} Person(string name):name_(name){cout<<"Person "<<name_<<" is created."<<endl;f=1;} virtual ~Person(){ if(f==1) cout<<"Person "<<name_<<" is erased."<<endl; if(f==0) cout<<"A person without name is erased."<<endl; } }; Person::static int f=0; class Teacher:virtual public Person { protected: string pos_; public: Teacher(string name,string pos):Person(name),pos_(pos){cout<<"Teacher "<<name_<<" "<<pos_<<" is created."<<endl;} ~Teacher(){cout<<"Teacher "<<name_<<" is erased."<<endl;} }; class Student:virtual public Person { protected: double sco_; public: Student(string name,double sco):Person(name),sco_(sco){cout<<"Student "<<name_<<" "<<sco_<<" is created."<<endl;} ~Student(){cout<<"Student "<<name_<<" is erased."<<endl;} }; int main(){ string name,pos; double sco; cin>>name>>pos>>sco; Person person; Person *p; p=new Teacher(name,pos); delete p; Person *q; q=new Student(name,sco); delete q; return 0; }哪错了？

这段代码有几个错误：

1. `Person::static int f=0;` 应该改为 `int Person::f=0;`，静态成员变量的定义需要在类外进行。

2. `Person person;` 这个对象没有给出名字，也没有传递参数，因此构造函数会使用默认构造函数，输出的信息不符合要求。

3. `Person *p; p=new Teacher(name,pos); delete p;` 这段代码会导致内存泄漏，因为使用 new 动态分配了内存，但是没有使用 delete 进行释放，应该在 delete 之前加上 `delete p; p= nullptr;`。

4. `Person *q; q=new Student(name,sco); delete q;` 同样会导致内存泄漏，应该在 delete 之前加上 `delete q; q = nullptr;`。

修改后的代码如下：

#include <iostream> 
#include <string>   

using namespace std;  

class Person {
    static int f; 
protected:     
    string name_; 
public:     
    Person(): f(0) { 
        cout << "A person without name is created." << endl;
    }     
    Person(string name): name_(name), f(1) {
        cout << "Person " << name_ << " is created." << endl;
    }     
    virtual ~Person() {    
        if (f == 1) 
            cout << "Person " << name_ << " is erased." << endl; 
        if (f == 0)    
            cout << "A person without name is erased." << endl;         
    } 
}; 

int Person::f = 0; 

class Teacher: virtual public Person { 
protected:     
    string pos_;  
public:     
    Teacher(string name, string pos): Person(name), pos_(pos) {
        cout << "Teacher " << name_ << " " << pos_ << " is created." << endl;
    }     
    ~Teacher() { 
        cout << "Teacher " << name_ << " is erased." << endl;
    }   
}; 

class Student: virtual public Person { 
protected:     
    double sco_; 
public:     
    Student(string name, double sco): Person(name), sco_(sco) {
        cout << "Student " << name_ << " " << sco_ << " is created." << endl;
    }     
    ~Student() {
        cout << "Student " << name_ << " is erased." << endl;
    }    
};   

int main() { 
    string name, pos; 
    double sco; 
    cin >> name >> pos >> sco; 
    Person person("Tom"); 
    Person *p; 
    p = new Teacher(name, pos); 
    delete p; p = nullptr;
    Person *q; 
    q = new Student(name, sco); 
    delete q; q = nullptr;
    return 0; 
}