exception_test.c++

#include <iostream>

class boing
{
public:
  ~boing()
  {
    std::cout << "bye bye" << std::endl;
  }
};


void foo()
{ 
  throw boing(); 
}   
  
int main()
{
  try
  {
    std::cout << "by value:" << std::endl;
    foo();
  }
  catch (boing e)
  {}

  try
  {
    std::cout << "by reference:" << std::endl;
    foo();
  }
  catch (boing &e)
  {}

  return 0;
}

exception_test.cxx

#include <iostream>

class boing
{
public:
  ~boing()
  {
    std::cout << "bye bye" << std::endl;
  }
};


void foo()
{ 
  throw boing(); 
}   
  
int main()
{
  try
  {
    std::cout << "by value:" << std::endl;
    foo();
  }
  catch (boing e)
  {
    std::cout << "caught it!" << std::endl;
  }

  try
  {
    std::cout << "by reference:" << std::endl;
    foo();
  }
  catch (boing &e)
  {
    std::cout << "caught it!" << std::endl;
  }

  return 0;
}

When this is compiled with GCC and run, it produced the following output:

by value:
caught it!
bye bye
bye bye
by reference:
caught it!
bye bye