8.3. ‘this’ pointer¶

The this pointer is a value that stores the address of the current object. Every non-static class member function is passed the this pointer. Whenever a member function or variable is used in a function, this-> is automatically added before the name, resulting in a member access expression.

class example
{
    int x;
    int y;

    public:

       void foo()
       {
           x = 6;       // same as this->x = 6;
           this->x = 5; // explicit use of this->
       }

       void foo() const
       {
         // x = 7; // Error: *this is constant
       }

       void foo(int x) // parameter x shadows the member with the same name
       {
           // x = x;       makes no sense in this function
           this->x = x; // unqualified x refers to the parameter
                        // 'this->' required for disambiguation
       }

       // No ambiguity in C++11 initializer syntax
       example (int x)
         : x(x),      // use parameter x to initialize member x
           y(this->x) // use member x to initialize member y
       {}

};

The this pointer can only be used in a member function. It is a compile error to use this outside of a member function.

Although this is a pointer, it is immutable. You can’t change it and have it point to some other object. It always points to the current object.

That is why the this pointer can’t be used in a static member function. Static members are members of the class. There is only a single copy that all objects of a class share. A static member has no way to determine which object instance the this pointer refers to.

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this pointer