polygon.cpp

《c＋＋大学教程实验指导书》源码

// Chapter 8 of C++ How to Program
// Coding Exercises
// polygon.cpp

// class Polygon definition
class Polygon {

public:
   Polygon( int = 0, int = 0 );
   ~Polygon();

   void addVertex( int, int );
   int getNumberOfVertices() const;

private:
   int *xPts;
   int *yPts;
   int numberOfVertices;

}; // end class Polygon

// default constructor
Polygon::Polygon( int x, int y )
{
   xPts = new int[ 1 ];
   yPts = new int[ 1 ];

   xPts[ 0 ] = x;
   yPts[ 0 ] = y;
   numberOfVertices = 1;

} // end class Polygon constructor

// destructor
Polygon::~Polygon()
{
   delete [] xPts;
   delete [] yPts;

} // end class Polygon destructor

// function addVertex definition
void Polygon::addVertex( int x, int y )
{
   int *copyX = new int[ numberOfVertices + 1 ];
   int *copyY = new int[ numberOfVertices + 1 ];

   for ( int i = 0; i < numberOfVertices; i++ ) {
      copyX[ i ] = xPts[ i ];
      copyY[ i ] = yPts[ i ];

   } // end for

   copyX[ numberOfVertices ] = x;
   copyY[ numberOfVertices ] = y;

   delete [] xPts;
   delete [] yPts;

   xPts = copyX;
   yPts = copyY;
   numberOfVertices++;

} // end function addVertex

// function getNumberOfVertices
int Polygon::getNumberOfVertices() const
{
   return numberOfVertices;

} // end function getNumVertices


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