Other Functionality

                          Other Functionality

Scope Resolution Operator

Scope Resolution Operator, denoted by the symbol :: (double colon) has two uses:

i) For defining member functions of class outside the class

ii) To access the global version of a variable

For defining member functions of class outside the class

We can define member function of a class outside the class definition using scope resolution operator (denoted as double colon sign ::)

Example of defining member function outside class

class abc

{

public:

void fun(); //member function of class abc

}; // class definition closed

void abc::fun() //member function fun of class abc is defined outside class definition

{

cout<<"hello";

}

void main()

{

abc ob;

ob.fun(); //member function fun called

}

To access the global version of a variable

Second use of scope resolution operator is to access the global version of a variable (this cannot be done in C). For example ::count means the global version of the variable count (and not the local variable count declared in that block)

Example of :: to access global version of a variable

#include<iostream.h>

#include<conio.h>

int m=10; //global m

void main()

{

clrscr();

int m=20; //m redeclared, local to main

{

int k=m;

int m=30; //m declared again,this time, local to inner block

cout<<"We are in inner block\n";

cout<<"k = "<<k<<"\n";

cout<<"m = "<<m<<"\n";

cout<<"::m = "<<::m<<"\n";

}

cout<<"\nWe are in outer block\n";

cout<<"m = "<<m<<"\n";

cout<<"::m = "<<::m<<"\n";

getch();

}

Output:

We are in inner block

k = 20

m = 30

::m = 10