copy constructor

 numer of constructor calls == numer of destructor calls

6-cia/src/geo2d-vz.cc

@@ -13,7 +13,8 @@ class Point
  public:
   Point(double x,double y); //constructor x/y position in the plane
                             //non default constructor
-  ~Point();                 //destructor no parameters
+  Point(const Point& other); //copy constructor
+ ~Point();                 //destructor no parameters
   double distance(Point other);
   
   static double distance(Point p,Point q);
@@ -32,6 +33,12 @@ Point::Point(double x,double y) //x,y parameter
  std::cout<<"constructor of Point "<<xc<<","<<yc<<"\n";
 }
 
+Point::Point(const Point& other)
+:xc(other.xc),yc(other.yc)
+{
+ std::cout<<"copy constructor of Point "<<xc<<","<<yc<<"\n";
+}
+
 Point::~Point()
 {
  std::cout<<"destructor of Point "<<xc<<","<<yc<<"\n";
@@ -47,10 +54,30 @@ double Point::distance(Point other)     //is a member of Point
 {
  return std::hypot(xc-other.xc,
                    yc-other.yc);
-}
+} //destructor of other
 
 //---------------------------------------------- Line
 
+
+/*
+constructor of Point 3,4 p 
+constructor of Point 6,8 q
+destructor of Point 6,8  other
+d=5
+destructor of Point 6,8  q  
+destructor of Point 3,4 p
+*/
+
+/* with own copy constructor
+constructor of Point 3,4 p
+constructor of Point 6,8 q
+copy constructor of Point 6,8 other
+destructor of Point 6,8       other
+d=5
+destructor of Point 6,8  q
+destructor of Point 3,4 p
+*/
+
 int main(int argc,char**args)
 {
  Point p(3,4);
@@ -58,8 +85,7 @@ int main(int argc,char**args)
 /*
  distance (3,4) -> (6,8) = sqrt(3*3+4*4)=sqrt(25)=5
 */ 
- auto d0=Point::distance(p,q);  //with static
- auto d1=p.distance(q);         //non static
+ auto d1=p.distance(q);          
  std::cout<<"d="<<d1<<"\n";
  return 0;
 }