How to sort a listBox in C#?

Question

I have typed numbers in a textbox and added them into a listBox. Now I need to order that listbox. This is my try:

int[] array = listBox1.Items.Cast<int>().ToArray<int>();
Array.Sort(array);
listBox1.Items.Clear();
foreach (int item in array)
{
    listBox1.Items.Add(item);
}

It throws an 'System.InvalidCastException'. But I can't figure it out HOW to solve it.

Answer 1

This is as simple as

listBox1.Sorted = true;

UPDATE

var array = new object[listBox1.Items.Count];
listBox1.Items.CopyTo(array, 0);
listBox1.Items.Clear();
var sortedArray = array.Select(n => (object)Convert.ToInt32(n)).OrderBy(n => n).ToArray();
listBox1.Items.AddRange(sortedArray);

Answer 2

You can use a lambda

var array = listBox1.Items.OfType<string>().Select(x => int.Parse(x))
                             .ToArray();

Answer 3

First, I want to say that it is not a good idea to store data inside a control. Always put your data inside types that can handle them like a List, Dictionary, etc. and then bind that to your listbox object. I guess you are working on windows forms. Then add a property to your form and put all your data in it.

something like this

public partial class Form1 : Form
{
List<string> _items = new List<string>(); // <-- Add this

public Form1()
{
    InitializeComponent();

    _items.Add("One"); // <-- Add these
    _items.Add("Two");
    _items.Add("Three");

    listBox1.DataSource = _items;
}
public void add()
{
 _items.Add("four");
 _items.Sort();
}
}

Answer 4

ListBox items can cast to string. So, You must cast it to string[], then convert to int[], then sort it and finally add sorted data to ListBox.

        string[] strArray = listBox1.Items.Cast<string>().ToArray();
        int[] intArray = strArray.Select(x => int.Parse(x)).ToArray();
        Array.Sort(intArray);
        listBox1.Items.Clear();
        foreach (int item in intArray)
        {
            listBox1.Items.Add(item);
        }

I hope this will be useful.