/* ECP: FILEname=fig14_28.cpp */
/* 1*/   // Base class shape.

/* 2*/   class Shape
/* 3*/   {
/* 4*/     protected:
/* 5*/       const char *Name;                  // Shape identifier.

/* 6*/     public:
/* 7*/       Shape( ) { }                       // Constructor.

/* 8*/       virtual double Area( ) const = 0;  // Area function.

/* 9*/       int operator < ( const Shape & Rhs ) const  // <
/*10*/           { return Area( ) < Rhs.Area( ); }

/*11*/       friend ostream & operator <<       // Output.
/*12*/               ( ostream & Output, const Shape & S );
/*13*/   };

/* 1*/   ostream & operator << ( ostream & Output, const Shape & S )
/* 2*/   {
/* 3*/       Output << S.Name << " of area " << S.Area( ) << "\n";
/* 4*/       return Output;
/* 5*/   }