关于类的问题，求解答

上述三个类，都有一个自我介绍函数printme（）,在各函数中分别输出..

如下：

#include <iostream>
using namespace std;

class CShape
{
public:
    virtual void printArea() = 0;
    void printMe() { cout << "I am CShape" << endl; }
};

class CCircle :public CShape
{
private:
    double radius;
public:
    CCircle(double r) { radius = r; }
    void printArea() { cout <<"面积："<< 3.1415926 * radius * radius; }
    void printMe() { cout << "I am CCircle" << endl; }
};

class CRectangle :public CShape
{
private:
    double length, width;
public:
    CRectangle(double l, double w) { length = l; width = w; }
    void printArea() { cout << "面积：" << length*width; }
    void printMe() { cout << "I am CRectangle" << endl; }
};

int main()
{
    CCircle c(2);
    c.printMe();
    c.printArea();
    CRectangle r(3, 4);
    r.printMe();
    r.printArea();
    return 0;
}

#include<iostream>
#define PI 3.14
using namespace std;
class CShape
{
public:
    virtual void printArea() = 0;
    static void printMe()
    {
        cout << "T am CShape" << endl;
    }
};
class CCircle :public CShape
{
public:
    CCircle(float n)
    {
        this->r = n;
    }
    void printMe()
    {
        cout << "T am CCircle" << endl;
    }
    void printArea()
    {
        cout << this->r*this->r*PI << endl;
    }
private:
    float r;
};
class CRectangle :public CShape
{
public:
    CRectangle(float l, float w)
    {
        this->lenth = l;
        this->width = w;
    }
    void printMe()
    {
        cout << "I an CRectangle" << endl;
    }
    void printArea()
    {
        cout << this->lenth*this->width << endl;
    }
private:
    float lenth;
    float width;
};
int main()
{
    CShape::printMe();
    CCircle c(9.9);
    c.printMe();
    c.printArea();
    CRectangle r(3, 4);
    r.printMe();
    r.printArea();
    return 0;
}