如何使用asp.net添加当前日期的天数

我想将天数添加到当前日期,例如我想输入数字的天数,而不是我选择我想在当前日期添加的日期是指天,周和月,但是当我选择天或周或者它显示的日期,但无法在当前日期添加它们可以任何人帮助我PLZ

 protected void TextBoxPredictDays_TextChanged(object sender, EventArgs e)
        {
            string selectPredictDays = DropDownList1.SelectedItem.Value;
            String Days1;
            int Result;
            Days1 = TextBoxPredictedClosing.ToString();
            if (selectPredictDays == "Days")
            {

                Result = Convert.ToInt32(TextBoxPredictDays.Text) * 1;
                TextBoxPredictedClosing.Text = Result.ToString();

            }
            else if (selectPredictDays == "Weeks")
            {

                Result = Convert.ToInt32(TextBoxPredictDays.Text) * 7;
                TextBoxPredictedClosing.Text = Result.ToString();
            }
            else if (selectPredictDays == "Months")
            {

                Result = Convert.ToInt32(TextBoxPredictDays.Text) * 30;
                TextBoxPredictedClosing.Text = Result.ToString();
            }

        }

这是我的设计代码

 
      
            Days
            Weeks
            Months
        

Konstantin Z.. 6

DateTime.Now.AddDays(int)- 数天
DateTime.Now.AddDays(int * 7)- 数周
DateTime.Now.AddMonths(int)- 数月

DateTime.Now.AddDays(int)- 数天
DateTime.Now.AddDays(int * 7)- 数周
DateTime.Now.AddMonths(int)- 数月