problem with exception behavior

[agarwaga]

/*
the code below prints copy constructor called three times , i can trace 2 times , one at throw in myfunction and one at catch(A e) in main .... can somebody explain the third

*/

#include <iostream>
#include <exception>
using namespace std;

class A{
  int a;

  public:
    A(){
    }

    A(A& gaurav){
      a  = gaurav.a;
      cout<<"copy constructor called \n";
    }
};

void myfunction() {
  A b;
  cout<<"here 1\n";
  throw b;
}

int main () {
  try
  {
     myfunction();
  }
  catch (int e)
  {
     cout<<e;
  }
   catch(A e)
  {
     cout<<"here";
  }
  return 0;
}

[hk_mp5kpdw]

Only prints twice for me.

[Daved]

It depends on the implementation. With my compiler (VC++ 7.1) it is only called twice. If you catch by reference (which is the preferred method anyway), it is only called once. It has to be called once because there needs to be a copy of the object that isn't destroyed when the stack is unwound.

If you have a debugger, put a breakpoint in the copy constructor and find out why you get three calls.

[agarwaga]

i am using Borland C++ 5.5.1 for Win32