OnPreRender vs Page_PreRender

Question

I knew about Page PreRender event and also about overriding OnPreRender, but didn't know existence of Page_PreRender method. Recently while going through this forum i found and search the difference between both but couldn't get much?

Here is my observation:

I have a page with label Label1.

Scenario 1:

    protected void Page_Load(object sender, EventArgs e)
    {
        Label1.Text = "load ";
    }
    protected override void OnPreRender(EventArgs e)
    {
        Label1.Text += "OnPreRender ";
        base.OnPreRender(e);
    }
    private void Page_PreRender(object sender, System.EventArgs e)
    {
        Label1.Text += "Page_PreRender ";
    }

value of Lable1 would be: load OnPreRender Page_PreRender

Scenario 2:

        protected void Page_Load(object sender, EventArgs e)
        {
            Label1.Text = "load ";
        }
        protected override void OnPreRender(EventArgs e)
        {
            base.OnPreRender(e);
            Label1.Text += "OnPreRender ";
        }
        private void Page_PreRender(object sender, System.EventArgs e)
        {
            Label1.Text += "Page_PreRender ";
        }

Note the call order of base.OnPreRender(e);

value of Lable1 would be: load Page_PreRender OnPreRender

I can only say base.OnPreRender(e) is calling Page_PreRender(), but isn't it private?

Can some one please tell, what is difference between both and when to use which? In general which one should be used?

Answer 1

The OnPreRender method of the page is responsible for raising the Page_PreRender event.

Usually you should just subscribe to the Page_PreRender event.

If you need to do some special processing before it's safe to raise the Page_PreRender event, then you can override the OnPreRender method and do the processing before calling base.OnPreRender(e).