Question

I got the following code:

class Book
{
public:
    void print();
    const Book &Book::get();
};
void Book::print()
{
    cout << "print()" << endl;
}
const Book &Book::get()
{
    cout << "get()" << endl;
    return *this;
}

Then I did:

Book b;
b.get().print(); // This did not work. Why is that?

Answer 1

It can call other functions, but not in this case.

You’re returning a const Book & from get(). This is then calling print(), which is a non-const function. To fix this, make print() const:

void print() const;

void Book::print() const
{
    cout << "print()" << endl;
}

This const ensures your object’s state will not be changed, which complies with the const object you return from get(). Note that it can change mutable members though, as that’s their whole purpose.

Edit:
By the way, the term you’re looking for is method chaining.