What is purpose of a "this" pointer in C++? [duplicate]

Question

What is purpose of this keyword. Doesn't the methods in a class have access to other peer members in the same class ? What is the need to call a this to call peer methods inside a class?

Answer 1

Two main uses:

1. To pass *this or this as a parameter to other, non-class methods.

   void do_something_to_a_foo(Foo *foo_instance);
   
   void Foo::DoSomething()
   {
       do_something_to_a_foo(this);
   }
   

2. To allow you to remove ambiguities between member variables and function parameters. This is common in constructors.

   MessageBox::MessageBox(const string& message)
   {
     this->message = message;
   }

   (Although an initialization list is usually preferable to assignment in this particular example.)