Anonymous Objects

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;
}
//---------------------------------------------------------------------------