#include<iostream>
using namespace std;
//基类
class People{
protected:
  char *name;
  int age;
public:
  People(char*, int);
};
People::People(char *name, int age): name(name), age(age){}
//派生类
class Student: public People{
private:
  float score;
public:
  Student(char*, int, float);
  void display();
};
//调用了基类的构造函数
Student::Student(char *name, int age, float score): People(name, age){
  this->score = score;
}
void Student::display(){
  cout<<name<<"的年龄是"<<age<<"，成绩是"<<score<<endl;
}
int main(){
  Student stu("小明", 16, 90.5);
  stu.display();
  return 0;
}

Student::Student(char *name, int age, float score): People(name, age)

Student::Student(char *name, int age, float score): People(name, age), score(score){}

Student::Student(char *name, int age, float score): People("李磊", 20)

#include<iostream>
using namespace std;
//基类
class People{
protected:
  char *name;
  int age;
public:
  People();
  People(char*, int);
};
People::People(){
  this->name = "xxx";
  this->age = 0;
}
People::People(char *name, int age): name(name), age(age){}
//派生类
class Student: public People{
private:
  float score;
public:
  Student();
  Student(char*, int, float);
  void display();
};
Student::Student(){
  this->score = 0.0;
}
Student::Student(char *name, int age, float score): People(name, age){
  this->score = score;
}
void Student::display(){
  cout<<name<<"的年龄是"<<age<<"，成绩是"<<score<<endl;
}
int main(){
  Student stu1;
  stu1.display();
  Student stu2("小明", 16, 90.5);
  stu2.display();
  return 0;
}

xxx的年龄是0，成绩是0
小明的年龄是16，成绩是90.5

#include<iostream>
using namespace std;
//基类
class People{
protected:
  char *name;
  int age;
public:
  People();
  People(char*, int);
};
People::People(): name("xxx"), age(0){
  cout<<"PeoPle::People()"<<endl;
}
People::People(char *name, int age): name(name), age(age){
  cout<<"PeoPle::People(char *, int)"<<endl;
}
//派生类
class Student: public People{
private:
  float score;
public:
  Student();
  Student(char*, int, float);
};
Student::Student(): score(0.0){
  cout<<"Student::Student()"<<endl;
}
Student::Student(char *name, int age, float score): People(name, age), score(score){
  cout<<"Student::Student(char*, int, float)"<<endl;
}
int main(){
  Student stu1;
  cout<<"--------------------"<<endl;
  Student stu2("小明", 16, 90.5);
  return 0;
}

PeoPle::People()
Student::Student()
--------------------
PeoPle::People(char *, int)
Student::Student(char*, int, float)

  Student s1; //Student是已声明的类名，s1是Student类的对象

#include <iostream>
#include <string>
using namespace std;
class Student//声明基类
{
public: //公用部分
  Student(int n, string nam ) //基类构造函数，与例11.5相同
  {
   num=n;
   name=nam;
  }
  void display( ) //成员函数，输出基类数据成员
  {
   cout<<"num:"<<num<<endl<<"name:"<<name<<endl;
  }
protected: //保护部分
  int num;
  string name;
};
class Student1: public Student //声明公用派生类Student1
{
public:
  Student1(int n, string nam,int n1, string nam1,int a, string ad):Student(n,nam),monitor(n1,nam1) //派生类构造函数
  {
   age=a;
   addr=ad;
  }
  void show( )
  {
   cout<<"This student is:"<<endl;
   display(); //输出num和name
   cout<<"age: "<<age<<endl; //输出age
   cout<<"address: "<<addr<<endl<<endl; //输出addr
  }
  void show_monitor( ) //成员函数，输出子对象
  {
   cout<<endl<<"Class monitor is:"<<endl;
   monitor.display( ); //调用基类成员函数
  }
private: //派生类的私有数据
  Student monitor; //定义子对象(班长)
  int age;
  string addr;
};
int main( )
{
  Student1 stud1(10010,"Wang-li",10001,"Li-sun",19,"115 Beijing Road,Shanghai");
  stud1.show( ); //输出学生的数据
  stud1.show_monitor(); //输出子对象的数据
  return 0;
}

This student is:
num: 10010
name: Wang-li
age: 19
address:115 Beijing Road,Shanghai
Class monitor is:
num:10001
name:Li-sun

  Student monitor;  //定义子对象 monitor(班长)

  Student1(int n, string nam,int n1, string nam1,int a, string ad):
    Student(n,nam),monitor(n1,nam1)

  Student1(int n, string nam,int n1, string nam1,int a, string ad): monitor(n1,nam1),Student(n,nam)