帮忙解释一下代码(在基类中声明虚类,及在基类的静态函数中创建派生类对象)

[西笑生]

代码我已经写了一部分
如何在基类的静态函数中创建派生类对象,请指教
#include "iostream"

using namespace std;

class Base
{
//public:Base();

public:
static Base* function();

virtual class Derived1* print1()=0;
virtual class Derived2* print2()=0;
virtual class Derived3* print3()=0;


};



class Derived1:public Base
{
public:Derived1(){cout<<"构造Derived1"<<endl;}

public:
virtual Derived1* print1();
virtual Derived2* print2();
virtual Derived3* print3();
};

class Derived2:public Base
{
public:Derived2(){cout<<"构造Derived2"<<endl;}

public:
virtual Derived1* print1();
virtual Derived2* print2();
virtual Derived3* print3();
};

class Derived3:public Base
{
public:Derived3(){cout<<"构造Derived3"<<endl;}

public:
virtual Derived1* print1();
virtual Derived2* print2();
virtual Derived3* print3();
};


Derived1* Derived1::print1()
{
cout<<"Derived1"<<endl;
return 0;
}
Derived2* Derived2::print2()
{
cout<<"Derived2"<<endl;
return 0;
}
Derived3* Derived3::print3()
{
cout<<"Derived3"<<endl;
return this;
}

Base* Base::function()
{
cout<<"function"<<endl;

return 0;
}

int main()
{


return 0;
}

[xmu_才盛]

#include "iostream"

using namespace std;

class Base
{
//public:Base();

public:
static Base* function(Base *p);

virtual class Derived1* print1()=0;
virtual class Derived2* print2()=0;
virtual class Derived3* print3()=0;


};


class Derived1:public Base
{
public:Derived1(){cout <<"构造Derived1" <<endl;}

public:
virtual Derived1* print1();
virtual Derived2* print2();
virtual Derived3* print3();
};

class Derived2:public Base
{
public:Derived2(){cout <<"构造Derived2" <<endl;}

public:
virtual Derived1* print1();
virtual Derived2* print2();
virtual Derived3* print3();
};

class Derived3:public Base
{
public:Derived3(){cout <<"构造Derived3" <<endl;}

public:
virtual Derived1* print1();
virtual Derived2* print2();
virtual Derived3* print3();
};


Derived1* Derived1::print1()
{
cout <<"Derived1::print1()" <<endl;
return 0;
}

Derived2* Derived1::print2()
{
cout <<"Derived1::print2()" <<endl;
return 0;
}
Derived3* Derived1::print3()
{
cout <<"Derived1::print3()" <<endl;
return 0;
}

Derived1* Derived2::print1()
{
cout <<"Derived2::print1()" <<endl;
return 0;
}

Derived2* Derived2::print2()
{
cout <<"Derived2::print2()" <<endl;
return 0;
}
Derived3* Derived2::print3()
{
cout <<"Derived2::print3()" <<endl;
return 0;
}


Derived1* Derived3::print1()
{
cout <<"Derived3::print1()" <<endl;
return 0;
}

Derived2* Derived3::print2()
{
cout <<"Derived3::print2()" <<endl;
return 0;
}
Derived3* Derived3::print3()
{
cout <<"Derived3::print3()" <<endl;
return 0;
}

Base* Base::function(Base *p)
{
cout <<"\nfunction" <<endl;

p=new Derived1();

return 0;
}

int main()
{

Base *p=new Derived1();
p->function(p);

return 0;
}

[xmu_才盛]

#include "iostream"

using namespace std;

class Base
{
//public:Base();

public:
static Base* function(Base *p);

virtual class Derived1* print1()=0;
virtual class Derived2* print2()=0;
virtual class Derived3* print3()=0;


};


class Derived1:public Base
{
public:Derived1(){cout <<"构造Derived1" <<endl;}

public:
virtual Derived1* print1();
virtual Derived2* print2();
virtual Derived3* print3();
};

class Derived2:public Base
{
public:Derived2(){cout <<"构造Derived2" <<endl;}

public:
virtual Derived1* print1();
virtual Derived2* print2();
virtual Derived3* print3();
};

class Derived3:public Base
{
public:Derived3(){cout <<"构造Derived3" <<endl;}

public:
virtual Derived1* print1();
virtual Derived2* print2();
virtual Derived3* print3();
};


Derived1* Derived1::print1()
{
cout <<"Derived1::print1()" <<endl;
return 0;
}

Derived2* Derived1::print2()
{
cout <<"Derived1::print2()" <<endl;
return 0;
}
Derived3* Derived1::print3()
{
cout <<"Derived1::print3()" <<endl;
return 0;
}

Derived1* Derived2::print1()
{
cout <<"Derived2::print1()" <<endl;
return 0;
}

Derived2* Derived2::print2()
{
cout <<"Derived2::print2()" <<endl;
return 0;
}
Derived3* Derived2::print3()
{
cout <<"Derived2::print3()" <<endl;
return 0;
}


Derived1* Derived3::print1()
{
cout <<"Derived3::print1()" <<endl;
return 0;
}

Derived2* Derived3::print2()
{
cout <<"Derived3::print2()" <<endl;
return 0;
}
Derived3* Derived3::print3()
{
cout <<"Derived3::print3()" <<endl;
return 0;
}

Base* Base::function(Base *p)
{
cout <<"\nfunction" <<endl;

p=new Derived1();

return 0;
}

int main()
{

Base *p=new Derived1();
p->function(p);

return 0;
}

[xmu_才盛]

#include "iostream"

using namespace std;

class Base
{
//public:Base();

public:
static Base* function(Base *p);

virtual class Derived1* print1()=0;
virtual class Derived2* print2()=0;
virtual class Derived3* print3()=0;


};


class Derived1:public Base
{
public:Derived1(){cout <<"构造Derived1" <<endl;}

public:
virtual Derived1* print1();
virtual Derived2* print2();
virtual Derived3* print3();
};

class Derived2:public Base
{
public:Derived2(){cout <<"构造Derived2" <<endl;}

public:
virtual Derived1* print1();
virtual Derived2* print2();
virtual Derived3* print3();
};

class Derived3:public Base
{
public:Derived3(){cout <<"构造Derived3" <<endl;}

public:
virtual Derived1* print1();
virtual Derived2* print2();
virtual Derived3* print3();
};


Derived1* Derived1::print1()
{
cout <<"Derived1::print1()" <<endl;
return 0;
}

Derived2* Derived1::print2()
{
cout <<"Derived1::print2()" <<endl;
return 0;
}
Derived3* Derived1::print3()
{
cout <<"Derived1::print3()" <<endl;
return 0;
}

Derived1* Derived2::print1()
{
cout <<"Derived2::print1()" <<endl;
return 0;
}

Derived2* Derived2::print2()
{
cout <<"Derived2::print2()" <<endl;
return 0;
}
Derived3* Derived2::print3()
{
cout <<"Derived2::print3()" <<endl;
return 0;
}


Derived1* Derived3::print1()
{
cout <<"Derived3::print1()" <<endl;
return 0;
}

Derived2* Derived3::print2()
{
cout <<"Derived3::print2()" <<endl;
return 0;
}
Derived3* Derived3::print3()
{
cout <<"Derived3::print3()" <<endl;
return 0;
}

Base* Base::function(Base *p)
{
cout <<"\nfunction" <<endl;

p=new Derived1();

return 0;
}

int main()
{

Base *p=new Derived1();
p->function(p);

return 0;
}

[JJZHK]

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