Question

I made a simple class to represent a door. To return the variables, I’m accessing them with the this pointer. With respect to just accessing variables, what’s the difference between accessing them with the this pointer and without?

class Door
{
protected:
    bool shut; // true if shut, false if not shut
public:
    Door(); // Constructs a shut door.
    bool isOpen(); // Is the door open?
    void Open(); // Opens the door, if possible. By default it
    // is always possible to open a generic door.
    void Close(); // Shuts the door.
};
Door::Door()
{}
bool Door::isOpen()
{
    return this->shut;
}
void Door::Open()
{
    this->shut = false;
}
void Door::Close()
{
    if(this->isOpen()) this->shut = true;
}

There may or may not be a difference here, but what about for more complex classes?

Answer 1

Nothing. The this pointer is automatically added if you exclude it.

You only have to use it if you’re doing something like this:

void Door::foo(bool shut)
{
    this->shut = shut; // this is used to avoid ambiguity
}

More usages

---

A brief overview:

Think of methods as functions that pass a pointer as their first argument.

void Door::foo(int x) { this->y = x; } // this keyword not needed

is roughly equivilent to

void foo(Door* this_ptr, int x) { this_ptr->y = x; }

Methods just automate this.