You can use this to subtract and add days to the existing data may be in your in a text box. Once you use these methods you get the values and u can print them or you can set teh text box with a fresh value.
using System;
class Program
{
static void Main()
{
Console.WriteLine("Today: {0}", DateTime.Today);
DateTime y = GetYesterday();
DateTime z = GetTomorrow();
Console.WriteLine(y,z);
}
/// <summary>
/// Gets the previous day to the current day.
/// </summary>
static DateTime GetTomorrow()
{
// Add 1 to now
return DateTime.Today.AddDays(1);
}
static DateTime GetYesterday()
{
// Add -1 to now
return DateTime.Today.AddDays(-1);
}
}