own copy constructor

6-cia/src/geo2d-bb.cc

@@ -11,6 +11,7 @@ class Point
 {
  public:
   Point(double x,double y); //non-default constructor           no return value
+  Point(const Point& other); //copy constructor
   ~Point();                 //destructor never with parameters no return value
   static double distance(Point p,Point q);
   double distance(Point other);    //non static instance method
@@ -28,6 +29,21 @@ Point::Point(double x,double y)
  std::cout<<"constructor Point "<<xc<<","<<yc<<"\n";
 }
 
+
+Point::Point(const Point& other)
+:xc(other.xc),yc(other.yc)
+{
+ std::cout<<"copy constructor Point "<<xc<<","<<yc<<"\n";
+}
+
+/* wrong copy constructor
+Point::Point(const Point& other)
+:xc(2*other.xc),yc(2*other.yc)
+{
+ std::cout<<"copy constructor Point "<<xc<<","<<yc<<"\n";
+}
+*/
+
 Point::~Point()
 {
  std::cout<<"destructor Point "<<xc<<","<<yc<<"\n";
@@ -39,29 +55,50 @@ double Point::distance(Point p,Point q)
                  //  |----|----|----|----------------private
 }
 
-double Point::distance(Point other)
+double Point::distance(Point other)  //copy constructor
 {
  return std::hypot(other.xc - xc,
                    other.yc - yc);
-}
+} //destructor of other
+
 
 /*
+with self made copy constructor
 constructor Point 5,7
 constructor Point 8,11
+copy constructor Point 8,11
 destructor Point 8,11
 d=5
 destructor Point 8,11
 destructor Point 5,7
+
+
+without own copy constructor
+constructor Point 5,7
+constructor Point 8,11
+destructor Point 8,11   of instance other
+d=5
+destructor Point 8,11
+destructor Point 5,7
+
+with wrong copy constructor
+constructor Point 5,7
+constructor Point 8,11
+copy constructor Point 0,0
+destructor Point 0,0
+d=8.60233
+destructor Point 8,11
+destructor Point 5,7
+
+
+
 */
 //---------------------------  use case
 int main(int argc,char** args)
 {
  Point p(5, 7);
  Point q(8,11);
-//distance p -> q sqrt(3*3 + 4*4)=sqrt(25)=5
-//auto d=Point::distance(p,q);
- auto d=p.distance(q);
-     // |----------|------------- instance
+ auto d=p.distance(q);  //other = q copy constructor
  std::cout<<"d="<<d<<"\n"; 
  return 0;
 }