Type of 'this' pointer in C++

 

　　

　　In C++, this pointer is passed as a hidden argument to all non-static member function calls. The type of this depends upon function declaration. If the member function of a class X is declared const, the type of this is const X* (see code 1 below), if the member function is declared volatile, the type of this is volatile X* (see code 2 below), and if the member function is declared const volatile, the type of this is const volatile X* (see code 3 below).

　　Code 1

#include<iostream>
class X 
{
   void fun() const 
   {
        // this is passed as hidden argument to fun(). 
        // Type of this is const X* 
   }
};

 

　　Code 2

#include<iostream>
class X 
{
   void fun() volatile 
   {
        // this is passed as hidden argument to fun(). 
        // Type of this is volatile X* 
    }
};

 

　　Code 3

#include<iostream>
class X 
{
   void fun() const volatile 
   {
     // this is passed as hidden argument to fun(). 
     // Type of this is const volatile X* 
    }
};

 

　　补充：

　　（1）In an ordinary nonconst member function, the type of this is a const pointer to the class type. We may change the value to which this points but cannot change the address that this holds. In a const member function, the type of this is a const pointer to a const class - type object. We may change neither the object to which this points nor the address that this holds.

　　（2）What is the purpose of a volatile member function in C++?【from stackoverflow】

　　

 

 

　　References:http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1905.pdf

 

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　　2013-11-26　　09:32:58