C++ operator -> in complex numbers case

Question

The problem is to implement class Cplx with two doubles x and y represent real and imaginary part of complex numbers.
One of the subtask is to implement operator -> with following description:

(z->re and z->im): access to the real and imaginary part of z(You must implement changing like z->re = 5).

I have troubles with operator -> I never really understand how it works so my question is: how -> works and when to use it and how to apply that idea in this problem.

Wasn't the *pointer to member* operator covered in the lectures? — Bathsheba, Jun 19 '18 at 07:48
If you really must name the doubles `x` and `y` implementing the behaviour `z->re` would be rather complicated. (Or I misunderstand the task description, it’s hard to follow, to be honest.) — idmean, Jun 19 '18 at 07:49
[Arrow operator (->) usage in C&C++](https://stackoverflow.com/questions/2575048/arrow-operator-usage-in-c) — Ehsan Panahi, Jun 19 '18 at 08:43

score 6 · Accepted Answer · answered Jun 19 '18 at 08:02

6

The following does what you ask... But not sure it is what you want:

template <typename T>
struct ReIm
{
    const ReIm* operator ->() const { return this; }
    ReIm* operator ->() { return this; }

    T re;
    T im;
};


struct Cplx
{
    double x;
    double y;

    ReIm<double> operator ->() const { return {x, y}; }
    ReIm<double&> operator ->() { return {x, y}; }
};

Demo

answered Jun 19 '18 at 08:02

Jarod42

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nice. way to go. – Kaveh Vahedipour Jun 19 '18 at 08:05
That’s what I had in mind, and to me it seems overly complicated in contrast to its benefit. On the other hand, it’s probably just an exercise. – idmean Jun 19 '18 at 08:07
I think it's more likely the OP misunderstood or failed the present their task properly. But it's always neat to see how even the most obscure requirement can sometimes be done in C++. – StoryTeller - Unslander Monica Jun 19 '18 at 08:15

score 1 · Answer 2 · answered Jun 19 '18 at 08:08

The -> operator works to dereference a pointer to an object and get a member variable/function in one operator. For example,

Cplx* cplxPointer = new Cplx();
cplxPointer->x = 5;

Is the same as

Cplx* cplxPointer = new Cplx();
(*cplxPointer).x = 5;

It just dereferences the pointer and then gets the member variable (or function if you want). Unless I misunderstood your question, the above should be able to help you complete your assignment.

C++ operator -> in complex numbers case

2 Answers2