this vs this in C

Question

I understand what this accomplishes, but how does it vary from *this?

Yes, I've Googled it and gone over it in my textbook, but I still don't grasp it...

Answer 1

This is a pointer, and *this is a pointer that has been dereferenced.

If you had a function that returned this, it would be a pointer to the current object, but a function that returned *this would be a "clone" of the current object, created on the stack unless you defined the method's return type to be a reference.

A small application that demonstrates the difference between working with copies and working with references:

#include <iostream>

class Foo
{
    public:
        Foo()
        {
            this->value = 0;
        }

        Foo get_copy()
        {
            return *this;
        }

        Foo& get_copy_as_reference()
        {
            return *this;
        }

        Foo* get_pointer()
        {
            return this;
        }

        void increment()
        {
            this->value++;
        }

        void print_value()
        {
            std::cout << this->value << std::endl;
        }

    private:
        int value;
};

int main()
{
    Foo foo;
    foo.increment();
    foo.print_value();

    foo.get_copy().increment();
    foo.print_value();

    foo.get_copy_as_reference().increment();
    foo.print_value();

    foo.get_pointer()->increment();
    foo.print_value();

    return 0;
}

Output:

1
1
2
3

You can see that when we act on a copy of our local object, the changes do not survive (since it is a whole distinct object), however operating on a reference or pointer does.