继承的作用是减少代码冗余，通过协调来减少接口和界面。
1.派生类的定义
<1>吸收基类成员
<2>改造基类成员
一是依靠派生类的继承方式来控制基类成员的访问、二是对基类成员或成员函数的覆盖。
<3>添加新的成员
2.类的继承方式
<1>.公有继承
#include <iostream>
using namespace std;
class vehicle
{
private:
float weight;
int wheels;
public:
vehicle(int in_wheels,float in_weight)
{
wheels=in_wheels;
weight=in_weight;
}
int get_wheels()
{
return wheels;
}
float get_weight()
{
return weight;
}
};
class car:public vehicle
{
private:
int passenger_load;
public:
car(int in_wheels,float in_weight,int people=5):vehicle(in_wheels,in_weight)
{
passenger_load=people;
}
int get_passenger()
{
return passenger_load;
}
};
int main()
{
car bm(4,100);
cout<<bm.get_wheels()<<endl;
cout<<bm.get_weight()<<endl;
cout<<bm.get_passenger()<<endl;
return 0;
}
结果：
4
100
5
<2>.私有继承
#include <iostream>
using namespace std;
class vehicle
{
private:
float weight;
int wheels;
public:
vehicle(int in_wheels,float in_weight)
{
wheels=in_wheels;
weight=in_weight;
}
int get_wheels()
{
return wheels;
}
float get_weight()
{
return weight;
}
};
class car:private vehicle
{
private:
int passenger_load;
public:
car(int in_wheels,float in_weight,int people=5):vehicle(in_wheels,in_weight)
{
passenger_load=people;
}
int get_passenger()
{
return passenger_load;
}
int get_wheels()
{
return vehicle::get_wheels();
}
int get_weight()
{
return vehicle::get_weight();
}
};
int main()
{
car bm(4,100);
cout<<bm.get_wheels()<<endl;
cout<<bm.get_weight()<<endl;
cout<<bm.get_passenger()<<endl;
return 0;
}
结果：
4
100
5
<3>.保护继承
#include <iostream>
using namespace std;
class vehicle
{
private:
int wheels;
protected:
float weight;
public:
vehicle(int in_wheels,float in_weight)
{
wheels=in_wheels;
weight=in_weight;
}
int get_wheels()
{
return wheels;
}
float get_weight()
{
return weight;
}
};
class car:protected vehicle
{
private:
int passenger_load;
public:
car(int in_wheels,float in_weight,int people=5):vehicle(in_wheels,in_weight)
{
passenger_load=people;
}
int get_passenger()
{
return passenger_load;
}
int get_wheels()
{
return vehicle::get_wheels();
}
int get_weight()
{
return weight;
}
};
int main()
{
car bm(4,100);
cout<<bm.get_wheels()<<endl;
cout<<bm.get_weight()<<endl;
cout<<bm.get_passenger()<<endl;
return 0;
}
结果：
4
100
5
3.派生类的构造函数和析构函数
4.派生类对基类成员的继承
通过访问声明调整访问域
<1>访问声明仅仅调整名字的访问，不可为它说明任何类型；成员函数在访问声明时，也不准说明任何参数
<2>对重载函数的访问声明将调整基类中具有该名得所有函数的访问域
<3>若派生类中具有与基类同名的函数，则基类中的此函数不能在派生类中进行访问声明
5.多重继承
<1>二义性和支配原则
作用域规则、支配规则
一个派生类中的名字将优先于它的基类中相同的名字
<2>赋值兼容原则
6.虚基类
例子：
#include <iostream>
using namespace std;
class Furniture{
public:
Furniture(){
cout<<"2333"<<endl;
}
void SetWeight(int i){
weight=i;
}
int GetWeight(){
return weight;
}
protected:
int weight;
};
class Bed:virtual public Furniture{
public:
Bed(){
cout<<"2444"<<endl;
}
void Sleep(){
cout<<"Sleeping...\n";
}
};
class Sofa:virtual public Furniture{
public:
Sofa(){
cout<<"2555"<<endl;
}
void WatchTV(){
cout<<"Watch TV\n";
}
};
class SleeerpSofa:public Bed,public Sofa{
public:
SleeerpSofa():Sofa(),Bed(){
}
void FoldOut(){
cout<<"Fold out the sofa. \n";
}
};
int main(){
SleeerpSofa ss;
ss.SetWeight(20);
cout<<ss.GetWeight()<<endl;
return 0;
}
结果:
233
2444
2555
20
7.类模板
理解类模板与模板类的关系:类模板+特定的数据类型=模板类
例题:
#include <iostream>
using namespace std;
template<class T>
class tem{
T *data;
int size;
public:
tem(int);
~tem(){
delete []data;
}
T& operator[](int i){
return data[i];
}
};
template<class T>
tem<T>::tem(int n){
data=new T[n];
size=n;
}
int main(){
tem<int> x(5);
int i;
for(i=0;i<5;i++)
x[i]=i;
for(i=0;i<5;i++)
cout<<x[i]<<' ';
cout<<endl;
return 0;
}
结果：
0 1 2 3 4
来源：https://www.cnblogs.com/liujunming/p/4540950.html