CODEWITHSUNDEEP
c++pointersconstants
echo3
echo3

Reputation: 131

Class function that returns a pointer to itself while being const. c++

Here's what I've tried:

game* Reversi::clone() const{
    Reversi* ptr = this;
    return ptr;
}

But I receive the following error:

error: invalid conversion from ‘const Reversi*’ to ‘Reversi*’ [-fpermissive]
Reversi* ptr = this;

Thanks in advance.

Upvotes: 2

Views: 165

Answers (1)

songyuanyao
songyuanyao

Reputation: 172894

The type of this is const Reversi* inside the const member function. You can use a non-const member function,

game* Reversi::clone() {
    Reversi* ptr = this;
    return ptr;
}

or change the type of ptr to const Reversi*,

const game* Reversi::clone() const {
    const Reversi* ptr = this;
    return ptr;
}

BTW: Your code just make a copy of the pointer this, doesn't copy the content at all. That means the returned pointer will just point to the same object. You might want,

game* Reversi::clone() const {
    Reversi* ptr = new Reversi(*this); // use copy ctor here
    return ptr;
}

Note when you make a copy from this the member function could be const. This seems more reasonable because a clone method shouldn't change the status of the original object in general.

Upvotes: 3

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