How to access variables inside an object?

Question

I am creating an algorithm to fill up a train with animals based on their size and type.

Imagine an animal object in an animal class with a type and size.

/* 0 = Carnivore, Carnivores will eat other animals which are smaller or the same size.
 * 1 = Herbivore
 * Animal sizes 1, 3, 5 are currently available.
 * A trainwagon can fit a maximum of 10 points. The wagon needs to filled optimally.
 * A new wagon is added if there are still animals which need to board the train. 
 */

public Animal(int type, int size)
{
    this.type = type;
    this.size = size;
}

I need the value of an animal to sort them. So, I created an override ToString() method to get the value.

public override string ToString()
{
    string animalInformation = type.ToString() + size.ToString();
    return animalInformation.ToString();
}

I currently solved it by separating the characters of the string and converting them back to integers.

int animalType = Convert.ToString(animalInformation[0]); 
int animalSize = Convert.ToString(animalInformation[1]);

My question is: Is there another technique to access the variables in the animal object, because the double conversion impacts the performance of my algorithm in a unneccesary way.

`int type` and `int size` begs so urgently to be modelled as enums. — Uwe Keim, Mar 16 '20 at 12:51

score 1 · Accepted Answer · answered Mar 16 '20 at 13:01

Take another look at your constructor:

public Animal(int type, int size)
{
    this.type = type;
    this.size = size;
}

This means that type and size are data members of your Animal class, which means that any instance of Animal has a type or a size. this.type is not a variable, but rather a data member of an object, which is similar to a variable due to its changeability, but it's an inherent attribute of an object. If you do something like

Animal animal = new Animal(1, 1);

and then you cannot reach animal.type, that means that animal.type is not public, but rather private or protected. You would be able to reach it if it were public. However, don't change it to public, it's good if you protect your fields from some problematic accesses I'm not describing at this point. Instead, you can define getters, like

public int getType() {
    return this.type;
}

public int getSize() {
    return this.size;
}

or some readonly properties and get the values by these.

JonasH · Answer 2 · 2020-03-16T13:22:20.547

Unless there is some detail not evident from the question, you should just create properties for the fields, i.e.

public readonly struct Animal
{
    public int Type { get; }
    public int Size { get; }

    public Animal(int type, int size)
    {
        Type = type;
        Size = size;
    }
}

Sorting can be done with linq. 'ThenBy(...)' is only needed if you need to sort by both properties:

var sortedAnimals = animals.OrderBy(animal => animal.Type).ThenBy(animal => animal.Size);

As mentioned in the comments, if you only want to allow some values for type and size, you should probably use enums. Or at least validate the arguments and throw an exception if the validation fails.

How to access variables inside an object?

2 Answers2