How destructor is executed here?

[venkatacplpl]

#include<iostream>
using namespace std;


class singleton
{
     int a ;
     
     static int count;
     //static singleton*ptr;
       
    singleton():a(0)
    {
    
    }
    ~singleton()
    {
        cout<<"I am in destructor"<<endl;
    }
public:    
    void display()
    {
         cout<<"a is "<<a<<endl;
         
    }
    
  
static singleton* createinstance()
   {
      if(count==0)
      {  static singleton instance;
      return &instance;
      }
      
      else
      {
          cout<<"Sorry one instance is already created"<<endl;
          return NULL;
      }
   }
  
};
/
int singleton::count=0;
int main()
{
       singleton*ptr=singleton::createinstance();
     ptr->display();      
       return 0;
       
}

Hi All I was going singleton design pattern and wrote the above program and executed and output is
a is 0
I am in destructor


I am really clueless why ptr destructor is called here,am really getting mad with this output.how destructor came into picture?,Please help

Thanks
Prasad

[MikeyBoy]

Please use code tags when posting code, to make it readable:

http://www.cplusplus.com/articles/jEywvCM9/

[S G H]

I think the distructor is being called after main() has returned.

[ShodanHo]

Checkout:
http://stackoverflow.com/questions/2204608/does-c-call-destructors-for-global-and-class-static-variables

Seems like the standard says that the destructor is called for static objects after returning from main() or when exit() is called.