Which of the following operator is overloaded for object cout?

#include<iostream.h> 
class Tab
{
      int x; 
    public:
      Tab();
     ~Tab();
      void Show() const;
};
Tab::Tab()
{
    x = 25;
}
void Tab::Show() const
{
    cout<< x;
}
int main()
{
    Tab objB;
    objB.Show();
    return 0; 
}

#include<iostream.h> 
class CuriousTab
{
    int x, y; 
    public:
    CuriousTab(int xx)
    {
        x = ++xx;
    } 
    ~CuriousTab()
    {
        cout<< x - 1 << " ";
    }
    void Display()
    {
        cout<< --x + 1 << " ";
    } 
};
int main()
{
    CuriousTab objCuriousTab(5);
    objCuriousTab.Display();
    int *p = (int*) &objCuriousTab;
    *p = 40;
    objCuriousTab.Display();
    return 0; 
}

#include<iostream.h>
class CuriousTabBase
{   
    public:
    CuriousTabBase()
    {
        cout<< "Base OK. "; 
    }
    virtual ~CuriousTabBase()
    {
        cout<< "Base DEL. "; 
    }
};
class CuriousTabDerived: public CuriousTabBase
{
    public:
    CuriousTabDerived()
    { 
        cout<< "Derived OK. "; 
    }
    ~CuriousTabDerived()
    { 
        cout<< "Derived DEL. "; 
    }
};
int main()
{
    CuriousTabBase *basePtr = new CuriousTabDerived();
    delete basePtr;
    return 0;
}

#include<iostream.h> 
class AreaFinder
{
    float l, b, h; 
    float result; 
    public:
    AreaFinder(float hh = 0, float ll = 0, float bb = 0) 
    {
        l = ll; 
        b = bb; 
        h = hh;
    }
    void Display(int ll)
    {
        if(l = 0)
            result = 3.14f * h * h; 
        else
            result = l * b; 
        cout<< result; 
    }
};
int main()
{
    AreaFinder objAF(10, 10, 20);
    objAF.Display(0); 
    return 0; 
}

#include<iostream> 
enum curioustab
{
    a=1, b, c
};
int main()
{
    int x = c;
    int &y = x;
    int &z = x;
    y = b;
    std::cout<< z--;
    return 0; 
}