继承:A作为一个基类,B作为一个A的派生类,则称为B继承A,A派生B
- 派生类拥有基类的所有成员函数和成员变量
- 派生类可以通过对基类进行修改和扩充得到
- 派生类一经定义,便可以独立使用,不依赖于基类
- 派生类哥哥成员函数中不可以访问基类的private
派生类写法:
class B:public A{...}
派生类对象的内存空间
派生类对象体积 = 基类对象体积+派生类对象自己的成员变量体积
(派生类对象包含基类对象)
#include<iostream>
#include<string>
using namespace std;
class Student{
private:
string name;
string ID;
int age;
char gender;
public:
void printfinfo();
void setinfo(const string& s1,const string& s2,int n, char ch);
string getname(){
return name;}
};
class CStudent:public Student
{
private:
string department;
public:
void printfinfo();
void setinfo(const string& s1,const string& s2,int n, char ch,const string& s3);
void qualified(){
cout<<"qualified for baoyan\n";
}
};
void Student::printfinfo()
{
cout<<name<<"("<<ID<<", "<<gender<<")"<<" is "<<age<<" years old ";
}
void Student::setinfo(const string& s1,const string& s2,int n,char ch)
{
name = s1;
ID =s2;
age = n;
gender = ch;
}
void CStudent::printfinfo()
{
Student::printfinfo();
cout<<", he is in "<<department<<" department";
}
void CStudent::setinfo(const string& s1,const string& s2,int n,char ch,const string& s3)
{
Student::setinfo(s1,s2,n,ch);
department = s3;
}
int main()
{
CStudent s1;
s1.setinfo("Jeff","2018224042",20,'M',"BME");
s1.printfinfo();cout<<endl;
cout<<s1.getname()<<" is ";
s1.qualified();
}
- 派生类也写同名函数,在同名函数里调用基类同名函数,这种叫覆盖。