Incrementing variables in ASP.net on every button click - asp.net

Question

I want to increment date in every click ASP.NET.
But Every time the page posts back, it is essentially starting over from scratch - anything initialized to 0.
I need to persist a value across postbacks but I don't how to do that. I would appreciate for any help.
Here is what I'am trying to do:
int myNumber = 0;
protected void Button1_Click1(object sender, EventArgs e)
{
lblDate.Text = DateTime.Now.StartOfWeek(DayOfWeek.Monday).AddDays(myNumber).ToShortDateString();
myNumber++;
}
Update:
My finaly goal is to get next weeks first day with next button and Previous week, I mean I want to forword and backword...
public int NextCount
{
get { return ViewState["Count"] != null ? (int)ViewState["Count"] : 7; }
set { ViewState["Count"] = value; }
}
protected void btnNext_Click1(object sender, EventArgs e)
{
lblsum.Text = DateTime.Now.StartOfWeek(DayOfWeek.Monday).AddDays(NextCount).ToShortDateString();
NextCount = NextCount+7;
}
protected void btnPrevious_Click(object sender, EventArgs e)
{
lblsum.Text = DateTime.Now.StartOfWeek(DayOfWeek.Monday).AddDays(NextCount).ToShortDateString();
NextCount = NextCount - 7;
}
But When I click Prev button .. there is delay with one click after two or three Click then reaction coming the same with next button when you click from prev to next. Maybe I have to store it in session?

Answer 1

I have updated your code below by using ViewState to handle this. Other easiest option would be storing the same in Session, Cache or Cookie.
While storing a value in ViewState, it will create a hidden field
in the page and store the value to maintain it across the postback.
public int NextCount
{
get { return ViewState["NextCount"] != null ? (int)ViewState["NextCount"] : 0; }
set { ViewState["NextCount"] = value; }
}
protected void btnNext_Click1(object sender, EventArgs e)
{
NextCount = NextCount+7;
lblsum.Text = DateTime.Now.StartOfWeek(DayOfWeek.Monday).AddDays(NextCount).ToShortDateString();
}
protected void btnPrevious_Click(object sender, EventArgs e)
{
NextCount = NextCount - 7;
lblsum.Text = DateTime.Now.StartOfWeek(DayOfWeek.Monday).AddDays(NextCount).ToShortDateString();
}