I have dynamically created checkbox. I have an option "Select All". How do I select all the dynamically created checkboxes in c#?

How to select all the dynamic checkboxes which have been created?

protected void chkbox_CheckedChanged(object sender, EventArgs e)
        {
            CheckBox chkBtn = new CheckBox();
            chkBtn = sender as CheckBox;
            selectedTypeId.Add(Convert.ToInt16(chkBtn.Name));
            foreach(int id in selectedTypeId)
            {
                Console.WriteLine(id);

            }
        }