C# Help

[mdb08]

I am stuck on a problem where I am being required to use IComparable, but I'm not sure why, can anyone help me?

This is how the problem has been worded to me

You should then ensure that the animals in the displayed list are sorted by the name of the animal using the List Sort method

This is the code I have in the main program

Spoiler

namespace Animals
{
public partial class AnimalForm : Form
{
List<NamedAnimal> animals = new List<NamedAnimal> {new Dog("Doggy"), new Cat("Candy"), new Horse("Horsey"), new Duck("Ducky"), new Cow("Mooo Machine")};

animals.Sort();


public AnimalForm()
{
InitializeComponent();
}

private void AnimalForm_Load(object sender, EventArgs e)
{
for (int i = 0; i < animals.Count; i++)
{
listBoxAnimal.Items.Add(animals.Name);
}
}

private void listBoxAnimal_SelectedIndexChanged(object sender, EventArgs e)
{
// Get selected index
int selection = listBoxAnimal.SelectedIndex;
// Now update display with information from this object
NamedAnimal animal = animals[selection];
pictureBox.Image = animal.Picture;
labelSpecies.Text = animal.Species;
labelSound.Text = animal.Sound;
labelLegs.Text = animal.NumberOfLegs.ToString();
lblnotes.Text = animal.GetNotes();
}
}
}

and the NamedAnimal class

Spoiler

namespace Animals
{
class NamedAnimal : Animal, IComparable<NamedAnimal>
{
string _Name;

public NamedAnimal(string species,
string imageName,
string sound,
int numberOfLegs)
: base(species, imageName, sound, numberOfLegs)
{
_Name = "Unnamed " + species;
}

public NamedAnimal(string name,
string species,
string imageName,
string sound,
int numberOfLegs)
: base(species, imageName, sound, numberOfLegs)
{
_Name = name;
}

public string Name
{
get
{
return _Name;
}
}

public virtual string GetNotes()
{
return "No notes avaliable";


}

public int CompareTo(NamedAnimal otherAnimal)
{
return _Name.CompareTo(otherAnimal.Name);
}


}
}

 

[mdb08]

It uses CompareTo from IComparable to compare two items and determine which should come first. Otherwise how would it know how you wanted the items sorted?

Sorry, what I mean is I understand the concept, but the code doesn't work, and I'm not sure why the code doesn't work

 

[mdb08]

try moving animals.Sort(); into AnimalForm_Load

failing that, elaborate on "doesn't work"

Thank you for that, it now doesn't produce a red line error. However, this may seem like a stupid question but it should now sort the animal names into alphabetical order?

 

[mdb08]

Dunno - just winging it without actually running your code

I think maybe Sort returns a result, and you're meant to use that result to bind your list?

Thank you for your help I do appreciate it, and understand the limitations of only having part of it.

Sort() is a void, it just sorts the generic list into the order specified by the implementation of CompareTo

It should sort the list and add it, in order, to the listBox.

Oh, and some syntax language usage, as that for() loop is making me itch:

I didn't write the forloop but will make the changes I don't however, fully understand what you mean. As when I run the program the animals are not sorted into alphabetical order :S

Thank you for the help though its muchly appreciated

 

[mdb08]

this works

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            List<Whatever> whatevers = new List<Whatever>();
            whatevers.Add(new Whatever("b"));
            whatevers.Add(new Whatever("a"));
            whatevers.Add(new Whatever("c"));

            whatevers.Sort();

            foreach (Whatever whatever in whatevers)
            {
                this.listBox1.Items.Add(whatever.Name);
            }
        }
    }

    class Whatever : IComparable<Whatever>
    {
        public Whatever(string name)
        {
            this.Name = name;
        }

        public string Name { get; set; }

        public int CompareTo(Whatever other)
        {
            return Name.CompareTo(other.Name);
        }
    }

Thanks for that, it appears my code was right, it was simply I was adding them to the list box and then sorting them, without updating the list box. Amateurish really