Answers for "what is the purpose of using pointer in c++"

pointer c++

int myvar = 6;
int pointer = &myvar; // adress of myvar
int value = *pointer; // the value the pointer points to: 6

what is this pointer in c++

Every object in C++ has access to its own address through an important pointer called this pointer.
 The this pointer is an implicit parameter to all member functions. 
Therefore, inside a member function,
 this may be used to refer to the invoking object.

Friend functions do not have a this pointer,
 because friends are not members of a class. 
Only member functions have a this pointer.