Sorting a Listbox of dates in the form dd/mm/yyyy in C#-CodePudding

I have a listbox and a (annual holiday) date picker. The user chooses the date and adds it to the Listbox. I then want to sort the Listbox from earliest to latest date. I tried using sorted Listbox but that did not work as it sorts like they are alphabetic strings. I then used unsorted Listbox and found some code and changed it to sort the box manually but again this is alphabetical. I am using the date as dd/mm/yyyy each date on a new line e.g.

If I have:

then I want the listbox to show me

what I get is the following where it sorts from left to right rather than year then month then day

At present I use the following code to add and then sort but there must be an easy way to sort this.

void Btn_add_holidayClick(object sender, EventArgs e)
        {
        lstbx_annual_hol.Items.Add(DatePick_Hol_Date.Value.Day.ToString("D2")   "/"  
                                       DatePick_Hol_Date.Value.Month.ToString("D2")   "/"  
                                       DatePick_Hol_Date.Value.Year.ToString()  "\n");  

            SortAnnualHoliday();
        }
        
        void SortAnnualHoliday()
        {
            ArrayList arList = new ArrayList(); 

            foreach (object obj in lstbx_annual_hol.Items)
            {
                arList.Add(obj);
            }
            
            arList.Sort(); 

            lstbx_annual_hol.Items.Clear();

            foreach(object obj in arList)
            {
                lstbx_annual_hol.Items.Add(obj); 
            }
        }

Thanks in advance for any advice and solutions even if you think I should do it a completely different way.

CodePudding user response：

You get this result because it tries to sort a list of strings not dates. For your purpose you should convert the strings back to dates, sort them, and convert the sorted list to string again:

void SortAnnualHoliday()
    {
      List<string> arList =lstbx_annual_hol.Items.Cast<string>()
        .Select(x => { DateTime.TryParseExact(x, "dd/MM/yyyy", new CultureInfo("en-US"), DateTimeStyles.None, out var y); return y; })
        .OrderBy(x => x)
        .Select(x => x.ToString("dd/MM/yyyy"))
        .ToList();
      lstbx_annual_hol.Items.Clear();
      lstbx_annual_hol.Items.AddRange(arList.ToArray());
    }

CodePudding user response：

Create a List<DateTime> so that you can SORT it based on the dates within. You can use a BindingSource to attach the List to your ListBox, making it update whenever changes are made.

Something like:

public partial class Form2 : Form
{

    private List<DateTime> dates = new List<DateTime>();
    private BindingSource source = new BindingSource();

    public Form2()
    {
        InitializeComponent();
        source.DataSource = dates;
        lstbx_annual_hol.FormatString = "d";
        lstbx_annual_hol.DataSource = source;
    }

    private void Btn_add_holidayClick(object sender, EventArgs e)
    {
        dates.Add(DatePick_Hol_Date.Value);
        dates.Sort();
        source.ResetBindings(false);
    }

}