Special operators in explicit constructor c++

Question

I'm new to c++ and i'm practicing myself on classes and objects. I've made a program which includes operator overloading and it has an "explicit constructor". I've tried it with a lots of different values and it's working properly, but my explicit constructor differs itself a bit from my teacher's answer. Teacher's answer:

class Ventilator {
int maxrot;
int rot;
int vert;
bool horiz;
public:
explicit Ventilator(int maxrot=500, int rot=0, int vert=0, int horiz=false): maxrot(abs(maxrot)),
   rot(rot<0?0:rot>abs(maxrot)?abs(maxrot):rot), vert(vert<-15||vert>15?0:vert),
   horiz(horiz)  { }

Mine is:

class Ventillator{
 int rotation;
 int vertikal;
 int maxrot;
int horiz;
public:
explicit Ventillator(int rotation = 10, int maxrot=100, int vertikal = 11, bool horiz = true):
    rotation(abs(rotation)), maxrot(abs(maxrot)), vertikal(abs(vertikal)), horiz(horiz){

    if (this->rotation > this->maxrot) this->rotation=this->maxrot;
    if (this->rotation < 0) this->rotation = 0;
    if (this->vertikal <= 15 && this->vertikal >=-15) this->vertikal=vertikal;
    else
        this->vertikal = 0;
    }

Aren't both ways quite the same? Isn't he just using special operators in order the code to be more compact?

The teacher's code allows a `vert` of `-5`, but yours would convert that to `+5`. — aschepler, Jun 12 '16 at 16:04

score 2 · Answer 1 · answered Jun 12 '16 at 15:49

2

The two examples achieve the same effect in this case. Using the initializer list only is (I would argue) generally more elegant because

It means the member can be const
The member is initialized to the correct value straight away. This can be important if another member initializer or the constructor body can throw.

However, I would argue that expressions with two ternary operators (?:) can be hard to read - I would probably have written a helper function to return the value to initialize rotation with.

answered Jun 12 '16 at 15:49

Martin Bonner supports Monica

28,528
3
51
88

I think i got it, thanks a lot! – specbk Jun 12 '16 at 16:03
Ternary operators are especially hard to read when you format them like your spacebar is broken! Judicious use of whitespace is critical. But I totally agree with you about writing a helper function. I do this frequently in my own code, but I've always kind of wondered about it, because I hardly ever see it in other people's code. – Cody Gray - on strike Jun 12 '16 at 16:56

score 1 · Answer 2 · edited Jun 12 '16 at 16:49

No, there is some difference, just ideological. Your solution is better because it is more readable—you can teach your teacher how to write beautiful code :)

Also, you rewrite that code like this:

#include <algorithm>
class Ventillator
{
    int rotation;
    int vertikal;
    int maxrot;
    int horiz;
    inline int place_in_range(int num, int max, int min)
    {
        return ( (std::max) ( ( (std::min)(max, num) ), min));
    }
    inline bool is_in_range(int num, int max, int min)
    {
        return num <= max && min >= num;
    }

public:
    explicit Ventillator(int rotation = 10, int maxrot=100, int vertikal = 11, bool horiz = true):
        rotation(place_in_range(abs(rotation), maxrot, 0)), maxrot(abs(maxrot)), vertikal( (is_in_range(vertikal, 15, -15) ? abs(vertical) : 0 )), horiz(horiz)
    {
    }
};

Thanks!! I will try it out! I thought that mine was wrong, i'm glad to hear it's not :)) — specbk, Jun 12 '16 at 16:20

Special operators in explicit constructor c++

2 Answers2