what is the basic use of scope resolution operator

Answer 1

used to define data member outside the class

Answer 2

this is scope resolution operator.
this is used to show the scope of a variable or a function...
for example.
class A
{
public:
void display();
};
void A::display ()
{
cout<<"hello world";
}

Answer 3

this is scope resolution operator.
this is used to show the scope of a variable or a function...
for example.
class A
{
public:
void display();
};
void A::display ()
{
cout<<"hello world";
}

Answer 4

it is used to declare some thing for example a member function out of its scope that is out of the class