Why does days difference between two datetimepicker give two different results?

Question

I have a really interesting issue. You can find the codes below;

The problem occurs when I run this Windows form application, the Duration textbox gives the result accurately; For instance; (30, Sep, 2023 - 01, Sep, 2023) + 1 = 30 Days. However, Sometimes and Howcome It doesn't accurately by giving the result and shows as 29 Days. Why do you think sometimes it doesn't read + 1 in the code?

// This function arranges duration
        private void ArrangeDuration()
        {
            DateTime endDate, startDate;
            TimeSpan duration;
            int dur;
            endDate = enddateTimePicker.Value;
            startDate = startdateTimePicker.Value;
            duration = endDate - startDate;
            dur = duration.Days + 1;
            durationtextBox.Text = dur.ToString() + " Days";
        }

// Arranges Duration Textbox when datetimepicker value changes
		private void startdateTimePicker_ValueChanged(object sender, EventArgs e)
        {
            ArrangeDuration();
            enddateTimePicker.Value = startdateTimePicker.Value;
        }

        private void enddateTimePicker_ValueChanged(object sender, EventArgs e)
        {
            ArrangeDuration();
        }

Answer 1

Hi @MUHAMMET GUNES , Welcome to Microsoft Q&A.

Maybe it's an effect of the timing part.

If the time portion of the is set to a time earlier than the time portion of the , this may result in a duration of 29 days instead of 30 days.

Try using:

duration = endDate.Date - startDate.Date;

Best Regards,

Jiale

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