This example uses anonymous Objects, that is, objects that don't have a name

An anonymous class is one that doesn't have a name. In the following example, both structures inside the TRectangle union are anonymous classes:

//--------------------------------------------------------------------------- #include <iostream> #include <conio> using namespace std; #pragma hdrstop //--------------------------------------------------------------------------- #pragma argsused // This rectangle can be identified by EITHER its location OR its dimensions union TRectangle { struct // Location { int x1; int y1; int x2; int y2; }; struct // Dimensions { double Length; double Height; }; }; //--------------------------------------------------------------------------- int main(int argc, char* argv[]) { TRectangle Recto; char Choice; cout << "You want to identify your rectangle by " << "its location or its dimensions?"; cout << "\n1 - Location"; cout << "\n2 - Dimension"; cout << "\nEnter your choice: "; cin >> Choice; if( Choice == '1' ) { cout << "\nEnter the location of the rectangle on a " << "Cartesian coordinate system\n"; cout << "First point\n"; cout << "X coordinate: "; cin >> Recto.x1; cout << "Y coordinate: "; cin >> Recto.y1; cout << "Second point\n"; cout << "X coordinate: "; cin >> Recto.x2; cout << "Y coordinate: "; cin >> Recto.y2; cout << "\nThe rectangle spans from A(" << Recto.x1 << ", " << Recto.y1 << ") to B(" << Recto.x2 << ", " << Recto.y2 << ").\n"; } else if( Choice == '2' ) { cout << "Enter the dimensions of the rectangle\n"; cout << "Length: "; cin >> Recto.Length; cout << "Height: "; cin >> Recto.Height; cout << "\nDimensions of the rectangle"; cout << "\nLength: " << Recto.Length; cout << "\nHeight: " << Recto.Height << endl; } else cout << "\nInvalid Choice"; return 0; } //---------------------------------------------------------------------------

Here is an example of running the program:

You want to identify your rectangle by its location or its dimensions?

1 - Location

2 - Dimension

Enter your choice: 1



Enter the location of the rectangle on a Cartesian coordinate system

First point

X coordinate: -4

Y coordinate: 2

Second point

X coordinate: 5

Y coordinate: 1



The rectangle spans from A(-4, 2) to B(5, 1).



Press any key to continue...