C++? ???? ?????? ???? ???, ???? ?????? ?? ??? ??????. ???? ??? ??? ??? ? ?? ?? ??? ???? ?? ?? ??? ?????. C++??? ?? ????? ?? ??? ??? ?? ???? ?????. ????? ??? ? ??? ? ? ??? ? ??? C++? ???? ???????.

1. ?? ????

?? ????? ??? ??? ?? ?? ??? ??? ??? ???? ??? ?? ???? ??, ???? ? ?? ?? ? ??? ???? ?? ?????. ??? ???? ??? ???? ????? ??? ????? ?? ?? ??? ????? ???? ?????. ?:

void print(int a){
    cout<<"int: "<<a<<endl;
}

void print(double b){
    cout<<"double: "<<b<<endl;
}

int main(){
    print(10); //調(diào)用print(int a)函數(shù)
    print(3.14); //調(diào)用print(double b)函數(shù)
    return 0;
}

print ??? ?? int ?? ? double ?? ????? ?? ?????? ?????. ? ???? ?? ??? ???? ????? ??? ???? ??? ?? ??? ?? ??? ?????. ?? ?? ????? ?? ??? ???? ????.

2. ?? ??

?? ??? ?? ???? ??? ???? ?? ????? ?? ???? ? ????. ?? ???? ??? ???? ?? ?? ??? ????? ??? ???? ???. ??? ? ?? ??? ?? ?? ?? ??? ?? ???? ????? ???? ?????. ?:

class Shape{
public:
    virtual void area(){ //定義虛函數(shù)area
        cout<<"This is a shape"<<endl;
    }
};

class Circle:public Shape{
public:
    void area(){//重寫(xiě)虛函數(shù)area
        cout<<"This is a circle"<<endl;
    }
};

class Rectangle:public Shape{
public:
    void area(){//重寫(xiě)虛函數(shù)area
        cout<<"This is a rectangle"<<endl;
    }
};

int main(){
    Shape *shape;
    Circle circle;
    Rectangle rectangle;
    shape = &circle;
    shape->area();//調(diào)用circle類(lèi)中的虛函數(shù)area
    shape = &rectangle;
    shape->area();//調(diào)用rectangle類(lèi)中的虛函數(shù)area
    return 0;
}

? ????? ?? ?? ??? ???? Shape ???? ?????. Circle ? Rectangle ???? Shape ???? ???? ? ?? ?? ?? ??? ?? ?????. Main ????? Shape ??? ?? ???? ???? Circle ??? Rectangle ??? ??? ???? ?? ??? ?? ?????. ?? ??? ?? ???? ?? ?? ?? ??? ?? ???? ?????? ?? ??? ?? "??? ????."? "??? ???????."???. ???? ??? ?? ??? ????.

3. ?? ?? ??

?? ?? ??? ?? ??? ?? ??? ?? ?? ?? ???? ???? ????? ??? ?? ???? ?? ?????. ?? ???? ?? ?? ??? ?? ?? ?? ???? ?? ????? ???. ?:

class Shape{
public:
    virtual void area() = 0;//定義純虛函數(shù)area
};

class Circle:public Shape{
public:
    void area(){
        cout<<"This is a circle"<<endl;
    }
};

class Rectangle:public Shape{
public:
    void area(){
        cout<<"This is a rectangle"<<endl;
    }
};

int main(){
    Shape *shape;
    Circle circle;
    Rectangle rectangle;
    shape = &circle;
    shape->area();//調(diào)用circle類(lèi)中的虛函數(shù)area
    shape = &rectangle;
    shape->area();//調(diào)用rectangle類(lèi)中的虛函數(shù)area
    return 0;
}

? ???? ?? ?? ?? ??? Shape ???? ???? ????. Circle ? Rectangle ???? Shape ???? ???? ?? ? ??? ???? ???. ??? ??? ??? ??? ?????. ? ???? ???? Circle ? Rectangle ??? ?? ???? ??? ?????.

??:

C++?? ???? ???? ??? ?? ??? ??? ? ? ?? ????? ?? ??? ?? ????? ???? ? ?? ?????. ???? ???? ??? ???? ????? ?? ??? ? ???, ??? ?? ?? ????? ? ?????. ?? ???????? ???? ??? ??? ????, ???? ???? ??? ??? ??? ? ??? ?? ????? ??? ???? ???.

? ??? C++?? ??? ??? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!