How to get the three previous dates

Check this


 DateTime dt = DateTime.Now;

            DateTime dt1 = dt.AddDays(-1); // WIll get previous date
 DateTime dt2 = dt1.AddDays(-1); // Will get the 2nd previous date

Like this use as per your need

If you are taking as string use as per below

string str = "16/07/2011";
  DateTime dt1 = DateTime.ParseExact(str, "dd/MM/yyyy", null);
  dt1 = dt1.AddDays(-1);
  DateTime dt2 = dt1.AddDays(-1);

You can loop too i tried in windows forms

 string text = "16/07/2011";
            DateTime parsed;
            CultureInfo culture = new CultureInfo("en-US");
            if (DateTime.TryParseExact(text, "dd/MM/yyyy", culture, DateTimeStyles.None, out parsed))
            {
                for (int i = 1; i <= 3; i++)
                {
                    Console.WriteLine(parsed.AddDays(-i).ToString("dd/MM/yyyy"));
                    if (i == 1)
                    {
                        textBox1.Text = parsed.AddDays(-i).ToString();
                    }
                    if (i == 2)
                    {
                        textBox2.Text = parsed.AddDays(-i).ToString();
                    }
                    if (i == 3)
                    {
                        textBox3.Text = parsed.AddDays(-i).ToString();
                    }

                }
            }