How to set default parameter as class object in c++?

Question

I want to set my function with class object parameter set as default. But when I try to do that it fails in compilation.

class base {
 // ...
};

int myfunc(         


        

Answer 1

A hack or ugly solution would be do a static cast from null:

#include 

class MyCustomClassType {
  int var;

  friend std::ostream &operator<<( 
         std::ostream &output, const MyCustomClassType &my_custom_class_type )
  {
    output << my_custom_class_type.var;
    return output;
  }
};

void function(
       MyCustomClassType my_custom_class_type = *static_cast( nullptr )
    ) 
{
  std::cout << my_custom_class_type << std::endl;
}

/**
 * To build it use:
 *     g++ -std=c++11 main.cpp -o main
 */
int main (int argc, char *argv[]) {
  function();
}

But, running this gives you directly a segmentation fault due dereferencing a null pointer. I am not sure when this would be useful.