Lab13 Solution

1. Design a stereo graphics class ( `CStereoShape` class), and meet the following requirements:
  + A virtual function `GetArea` , which can get the surface area of the stereo graphic, Here we let it print out `CStereoShape::GetArea()` and return a value of 0.0, which means that CStereoShape 's GetArea is called.
  + A virtual function `GetVolume` , which can get the volume of the stereo graphic, Here we let it print out `CStereoShape::GetVolume()` and return a value of 0.0, which means that CStereoShape 's GetVolume is called.
  + A virtual function`Show`, which print out the description of the stereo graphics. But here we let it print out `CStereoShape::Show()` , which means that Show of CStereoShape is invoked.;
  + A static private integer variable named `numberOfObject` , whose initial value is 0, which denotes the number of Stereo graphics generated by our program.
  + A method named `GetNumOfObject()` that returns the value of numberOfObject. 
  + Add constructor functions based on requirement

2. Design a cube class ( `CCube` class), which inherits the CStereoShape class and meets the
following requirements:
  + A no-arg constructor that creates a default Cube.
  + A constructor with parameters whose parameters correspond to the length, width, and height of the cube, respectively.
  + A copy constructor that creates a Cube object with the specified object of Cube .
  + Override `GetArea` 、`GetVolume` of the `CStereoShape` class to complete the calculation of the surface area and volume of the cube, respectively.
  + Override `Show()` of the `CStereoShape` class to print out the description (includes length, width, height, the surface area and volume )for the Cude object.

3. Design a sphere class ( `CSphere` ), which inherits from the StereoShape class and meets the following requirements:
  + A no-arg constructor that creates a default Sphere.
  + A constructor with parameters whose parameters correspond to the radius of thesphere.
  + A copy constructor that creates a `Sphere` object with the specified object of Sphere.
  + Override the GetArea and GetVolume of the CStereoShape class to complete thecalculation of the surface area and volume of the sphere, respectively.
  + Override `Show()` of the CStereoShape class to print out the description (includesradius, the surface area and volume )for the Sphere object.

4. Write a test program and complete at least the following tasks in the main functions:
  + Create a CCube object named **a_cube**, which the **length**, **width** and **height** are 4.0, 5.0, 6.0 respectively.
  + Create a CSphere object named **c_sphere**, which radius is 7.9.
  + Define the CStereoShape pointer **p**, point p to **a_cube**, and then print the information of **a_cube** to the terminal by **p**;
  + Point **p** to **c_sphere**, then print the information of **c_sphere** to the terminal by **p**.
  + Prints out the **number** of Stereo graphics created by the test program

+ Note that You may need to use the `setf ()` and `precision ()` formatting methods to
set the output mode.