Introduction - If you have any usage issues, please Google them yourself
The use of object-oriented methods and graphic design point class graphics classes (including Point class members), derived by the latter design round classes (including center, radius), square type (including upper left vertex, edge length) with the rectangular type (including left corner vertices, length and width), triangles class (with three vertices) while designing the relevant class constructor member data set/extraction operation function, the vertex display functions and girth and area calculation function, where the vertex functions and week display length and area calculation function in the graphic class should be defined as a pure virtual function. In the first four in the main function, namely to create all kinds of objects, invoke and execute the relevant member functions, observe and analyze the result of the program