設置datetimepicker的默認值，如果相等，則設置為0

Question

如果值等於默認日期“ Now”，我試圖將datetimepicker設置為0。 這就是我所擁有的，即使更改了值，它也始終返回null。

private string _BirthDate;

public Form1()
{
    InitializeComponent();
    dateTimePicker1.MaxDate = DateTime.Now; // Ensures no future dates are set.
    dateTimePicker1.Format = DateTimePickerFormat.Custom;
    //dateTimePicker1.Checked = true;
    dateTimePicker1.CustomFormat = dateTimePicker1.CustomFormat;
    dateTimePicker1.Value = DateTime.Now;
}

public string BirthDate
{
    set
    {
        if (dateTimePicker1.Value.Date != DateTime.Now)
        {
            _BirthDate = value;
        }
    }
    get { return _BirthDate; }
}

private void button1_Click(object sender, EventArgs e)
{
    string date = Convert.ToString(BirthDate); 
}

我知道DateTime類不能為null，但是要解決這個問題，我只想檢查該值是否為默認值，如果是，則將其設置為0。

Answer 1

您可以使DateTime為空

DateTime? date = null;

Answer 2

現在解決了所有問題，只需要進行調整。 就像你們所說的，我沒有設置值或屬性，所以無論如何它都是空的

private string _BirthDate;

        public Form1()
        {
            InitializeComponent();
            dateTimePicker1.MaxDate = DateTime.Now; // Ensures no future dates are set.
            dateTimePicker1.Format = DateTimePickerFormat.Custom;
            //dateTimePicker1.Checked = true;
            dateTimePicker1.CustomFormat = dateTimePicker1.CustomFormat;
            dateTimePicker1.Value = DateTime.Now;
        }
        public string BirthDate
        {
            set
            {
                if (dateTimePicker1.Value.Date == DateTime.Today)
                {
                    dateTimePicker1.CustomFormat = " ";

                }
                else
                {
                    _BirthDate = value;
                }
            }
            get { return _BirthDate; }
        }


        private void button1_Click(object sender, EventArgs e)
        {

           BirthDate = dateTimePicker1.Value.ToString();
        }