//窗體初始化事件
    private void Form1_Load(object sender, EventArgs e)
    {
        this.dateTimePicker1.Format = DateTimePickerFormat.Custom;
        this.dateTimePicker1.CustomFormat = " ";  //" "引號中間必須有空格
        //this.dateTimePicker1.Checked = false;
    }

    private void dateTimePicker1_ValueChanged(object sender, EventArgs e)
    {
        this.dateTimePicker1.Format = DateTimePickerFormat.Long;
        this.dateTimePicker1.CustomFormat = null;
    }

    //清空按鈕事件
    private void button1_Click(object sender, EventArgs e)
    {
        this.dateTimePicker1.Format = DateTimePickerFormat.Custom;
        this.dateTimePicker1.CustomFormat = " ";
        this.dateTimePicker1.Checked = false;
    }

    //讀取按鈕事件
    private void button2_Click(object sender, EventArgs e)
    {
        if(dateTimePicker1.Text==" ")
        {
            this.textBox1.Text = "日期為空！";
        }
        else
        {
            this.textBox1.Text = this.dateTimePicker1.Text;
        }
    }