__________ used to make a copy of one class object from another class object of the same class type.

#include<iostream.h> 
void MyFunction(int a, int b = 40)
{
    cout<< " a = "<< a << " b = " << b << endl;
}
int main()
{
    MyFunction(20, 30);
    return 0; 
}

#include<iostream.h>
long GetNumber(long int Number)
{
    return --Number;
}
float GetNumber(int Number)
{
    return ++Number;
}
int main()
{
    int x = 20;
    int y = 30;
    cout<< GetNumber(x) << " ";
    cout<< GetNumber(y) ;
    return 0; 
}

1. Pointer to a reference and reference to a pointer both are valid.
2. When we use reference, we are actually referring to a referent.

#include<iostream.h> 
class Tab
{
    int x, y; 
    public:
    void show(void);
    void main(void);
};
void Tab::show(void)
{ 
    Tab b;
    b.x = 2;
    b.y = 4;
    cout<< x << " " << y;
}
void Tab::main(void)
{
    Tab b;
    b.x = 6; 
    b.y = 8;
    b.show();
}
int main(int argc, char *argv[])
{
    Tab run;
    run.main();
    return 0; 
}