Scope Resolution Operator vs this Pointer in C++

In this tutorial, we will compare the Scope Resolution operation to this Pointer in C++ language.

Scope Resolution Operator

The Scope Resolution Operator in C++ programming language is usually denoted by (::). It is used in various Scenarios such as global variables, defining a function, accessing class static variables, multiple inheritances, referring to another class etc.

1. Accessing the Global and Local Variables with the same Terminology

Code:

#include<iostream> 
using namespace std;
int xyzz;
int main(){
  int x = 10; // Local x
  cout << "The value of global xyzz variable is " << ::xyzz;
  cout << "\nThe Value of local the same xyzz variables " << xyzz;  
  return 0;
}

Output:

The value of global xyzz variable is 0
The Value of local the same xyzz variables 0

2. Defining a Function Code outside of the Class

Code:

#include<iostream> 
using namespace std;
class A_b_c{
public: 
void fun();
};
void A_b_c::fun(){
   cout << "fun() called done over";
}
int main(){
   A_b_c a;
   a.fun();
   return 0;
}

Output:

fun() called done over

3. To access a Class of Static Variables

Code:

#include<iostream>
using namespace std;
class Test{
static int x;  
public:
    static int y;   
    void func(int x)  
    { 
cout << "static x value is " << Test::x;
cout << "\nlocal x value is " << x;  }
};
int Test::x = 1;
int Test::y = 2;
int main(){
    Test obj;
    int x = 3 ;
    obj.func(x);
    cout << "\nTesting for the value of ::y = " << Test::y;
return 0;
}

Output:

the static x value is 1
the local x value is 3
Testing for the value of::y = 2

4. Multiple Inheritances

Code:

#include<iostream>
using namespace std;
class A_b{
protected:
    int x;
Public:
    A_b() { x = 1576570; }
};
class B_c{
protected:
    int x;
Public:
    B_c() { x = 12220; }
};
class C_d: public A_b, public B_c{
Public:
   void fun()
   {
      cout << "A_b's x is " << A_b::x;
      cout << "\nB_c's x is " << B_c::x;
   }
};
int main(){
    C_d c;
    c.fun();
    return 0;
}

Output:

A_b's x is 1576570
B_c's x is 12220

5. In a particular Namespace Case

Code:

// Here, as we can see, there is no namespace std; hence we are
//using the scope resolution operator for the absence of namespace
#include<iostream>
int main(){
    std::cout << "Hello" << std::endl;
}

Output:

Cout and endl keys will be belonging to the std namespace.

6. Referring to a Class inside having Another Class

Code:

#include<iostream>
using namespace std;
class out_side{
public:
int xyzz;
class place_inside{
public:
int xyzz;
static int yzz; 
int foomo();
};
};
int out_side::place_inside::yzz = 5; 
int main(){
outside A;
outside::inside B;
}

Output:

//to refer to the class inside another no type no output here

this Pointer in C++

To know well about This operator in C++, we will look at objects and their orientation in C++; things get the identical or exact copy of their member class, and a code segment using the function will be called multiple times. This could be the reference of the code segment than the standard pointer reference, but the reference was not present in the early version of the C++ programming language.

Syntax (to return the calling object)

Test& Test::func (){
   //processing of the sum happens here
   return *this;
}

The below code depicts the case where a local variable name is as same as a member name

Code:

#include<iostream>
using namespace std;
class Test{
private:
   int xyxx;
public:
   void setX (int xyxx){
this->xyxx = xyxx;
   }
void print() { cout << "xyxx = " << xyxx << endl; }
};
int main(){
   Test obj;
   int xyxx = 20;
   obj.setX(xyxx);
   obj.print();
   return 0;}

Output:

xyxx = 20

In an instance where the reference to a local variable has been returned, the reference can be made to form chains of function calls on a unique single object copy of it.

Code:

#include<iostream>
using namespace std;
class Test{
private:
  int xyxx;
  int yxx;
public:
  Test(int xyxx = 0, int yxx = 0) { this->xyxx = xyxx; this->yxx = yxx; }
  Test &setX(int ab) { xyxx = ab; return *this; }
  Test &setY(int bc) { yxx = bc; return *this; }
  void print() { cout << "xyxx = " << xyxx << " yxx = " << yxx << endl; }
};
int main()
{
Test obj1(5, 5);
obj1.setX(10).setY(20);
obj1.print();
  return 0;
}

Output:

xyxx = 10 yxx = 20

Scope Resolution Operator vs this Pointer in C++