This keyword in C++

• This keyword in C++ is a pointer which points to the object.
• It is passed as an argument to functions which helps in accessing the object. It is used for a non-static function.
• There are different ways in which we can use this keyword in C++. They are
  1. To resolve the shadowing issue when this keyword is used.
  2. To access the data members of the current object.
  3. To access the currently executing object using this keyword.
  4. To call the member function of the current object.

To resolve the shadowing issue when this keyword is used:

• Before getting into the program, we need to know what shadowing is.
• Shadowing issue occurs when both the instance variable and local variable have the same name.
• Let us consider a program in C++ which is used in case of shadowing issues:

/ / program in C++ for above case
# include< iostream >
Using namespace std;
Class demo {
string s;
public:
demo ( string s )
{
/ / using this keyword
/ / to initialize the value
this - > s = s;
}
void display ( ) {
cout << s << endl; } ];
/ / main function
int main ( )
{
Demo d(“Hello world “);
d.display ( );
return 0;
}

Output:

Hello world

To access the data members of the current object

• By using this keyword, we can access the object and the data member associated with the object.
• Let us consider a program in C++ for the above scenario:

/ / program in C++
/ / to access the object using this keyword
# include <iostream>
Using namespace std;
class demo 
{
String s;
public :
demo ( string s )
{
/ / using this keyword
this - > s = s;
}
Void display ( )
{ 
Cout << this - > s << endl;
}
};
/ /class driver
int main ( )
{
demo d (“Hello world”);
d.display ( );
return 0;
}

Output:

Hello world

To access the currently executing object using this keyword:

• By using this keyword, we can access the currently executing object.
• We can chain function, and object can be deleted with the help of the member function.

/ / program in C++ for above scenario
# include <iostream>
Using namespace std:
class demo {
string s;
public :
demo (string s) {
/ / using this keyword to assign value 
this - > s = s;
}
Void display ( ) {
cout << s << endl;
}
void delete ( ) {
delete this;
} };
/ / main function
int main ( ) {
demo *d = new demo (“Hello world “);
d - > display ( );
d - > delete ( );
return 0;
}

Let us consider a program in C++ for the above scenario:

Output:

Hello world

To call the member function of the current object:

• This keyword is used to access the object of the class.
• It is also used to access the function associated with the object.
• Let us consider a program in C++:

/ / program in C++ using this keyword
/ / to call the function of current object
# include <iostream >
using namespace std;
class demo 
{
String s;
public:
demo ( string s )
{
/ / using this keyword 
this - > s = s;
}
void dis ( int );
void display ( );
};
void demo : : dis (int x)  {
/ / accessing the function the current object
for( int i = 0; i < x ; i++)  {
this - > display ( ); }
}
Void demo  : : display ( )  {
/ / access the string data member
Cout << this - > s <<endl;  }
/ / main function
int main ( ) {
demo d (“Hello world “);
d.dis ( 5 );
return 0;
}

Output:

Hello world
Hello world
Hello world
Hello world
Hello world

• Hence, we can conclude that this keyword can be used to To resolve the shadowing issue when this keyword is used.
• It is used to access the data member of the current class.
• To access the object which is currently executing.
• To call the function associated with the object.