How to get the current week starting date and add it to a combo box?

Question

I'm attempting to recreate a time sheet built on asp and I can't figure out how to get the current weeks starting date "6-13-2010" and have it populate a combo box can you help me with this I'm new to C# and asp programming.

score 31 · Accepted Answer · answered Jun 17 '10 at 14:56

31

DateTime startOfWeek = DateTime.Today.AddDays(-1 * (int)(DateTime.Today.DayOfWeek));

Regarding adding items to a DropDownList in ASP.NET, assuming you're using the webforms model, you would do something like

yourDropDown.Items.Add(new ListItem(yourText, yourValue));

answered Jun 17 '10 at 14:56

Anthony Pegram

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@Walter, no, it gives Sunday. – Anthony Pegram Mar 19 '15 at 02:39
My mistake, it gives Sunday, but in the code base, it was Saturday that I needed (not Sunday) – Walter Mar 19 '15 at 18:39
can you tell me why you multiply by -1 instead of adding simple minus sign? – Michael Brennt Jan 22 '16 at 22:49

Jason Berkan · Answer 2 · 2010-06-17T15:13:46.393

4

DateTime startOfWeek = Today.AddDays((int)Today.DayOfWeek * -1)

Likely an off by one error, since it is untested.

edited Jun 17 '10 at 15:13

answered Jun 17 '10 at 14:56

Jason Berkan

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It would not be off by one, it just wouldn't compile! – Anthony Pegram Jun 17 '10 at 15:02
4

That's what happens when a VB programmer tries to write C# code. :) – Jason Berkan Jun 17 '10 at 15:13
To get Sunday use: `DateTime startOfWeek = DateTime.Today.AddDays(-1 * (int)(DateTime.Today.DayOfWeek) - 1);` – Walter Mar 19 '15 at 01:11
@Walter, your revision will produce Saturday. – Anthony Pegram Mar 19 '15 at 02:40
Oops, it turns out that last Saturday and not last Sunday is what I needed, The code list above also had an off by one bug. Here is the updated code for last Saturday without the off by one bug `DateTime startOfWeek = DateTime.Today.AddDays(DateTime.Today.DayOfWeek == 0 ? 0 : (- 1 * (int)(DateTime.Today.DayOfWeek) - 1));` – Walter Mar 19 '15 at 18:47

score 1 · Answer 3 · answered Jun 17 '10 at 15:03

Here's an example that uses an iterator.

    /// <summary>
    /// Gets the dates that mark the beginning of each week from the specified start date until today.
    /// </summary>
    /// <param name="weekStart">The day of the week that marks the beginning of a week</param>
    /// <param name="startDate">A date that determines the earliest week in the result.</param>
    /// <returns></returns>
    public IEnumerable<DateTime> GetWeeks(DayOfWeek weekStart, DateTime startDate)
    {
        DateTime current = DateTime.Today.AddDays(weekStart - DateTime.Today.DayOfWeek);
        while(current >= startDate)
        {
            yield return current;

            // move to the previous week
            current = current.AddDays(-7);
        }
    }

    public void PopulateUI()
    {
        // in this example, Monday is considered the start of the week,
        // and the drop down list will be populated with the date of each monday starting with this week going back to 1 year ago.
        ddlWeeks.DataSource = GetWeeks(DayOfWeek.Monday, DateTime.Today.AddYears(-1));
    }

You mentioned that you're pretty new to C#, so sorry if it seems confusing. Below is an alternative GetWeeks function that is not defined as an iterator.

    public List<DateTime> GetWeeks(DayOfWeek weekStart, DateTime startDate)
    {
        List<DateTime> result = new List<DateTime>();

        DateTime current = DateTime.Today.AddDays(weekStart - DateTime.Today.DayOfWeek);
        while (current >= startDate)
        {
            result.Add(current);

            // move to the previous week
            current = current.AddDays(-7);
        }

        return result;
    }

score 0 · Answer 4 · answered Jun 17 '10 at 14:58

0

DateTime.Now.Date.AddDays(-1 * (Int32)DateTime.Now.DayOfWeek)

answered Jun 17 '10 at 14:58

decyclone

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How to get the current week starting date and add it to a combo box?

4 Answers4

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