Set DateTimePicker value to be null

Question

I am developing a WinForms UI with two DateTimePicker controls. Initially I want to set the value of the controls to null until a user selects a date. If the us

Answer 1

I think the best solution is to use the build-in checkbox that tell the user if a value is specified or not.

Set the control property ShowCheckBox = true

When you bind the value to it do something like

 if (value == DateTime.MinValue) {
    datePicker.Checked = false;
  } else {
    datePicker.Checked = true;
    datePicker.Value = value;
  }

When reading back the value check the Checked property.

If you don't like the displayed value when it's unchecked, you can combine that with the other suggestions.

  if (!datePicker.Checked) {
    // hide date value since it's not set
    datePicker.CustomFormat = " ";
    datePicker.Format = DateTimePickerFormat.Custom;
  } else {
    datePicker.CustomFormat = null;
    datePicker.Format = DateTimePickerFormat.Long; // set the date format you want.
  }