How can I change the time counter direction if to count up or down ?

Question

using System;  
using System.Collections.Generic;  
using System.ComponentModel;  
using System.Data;  
using System.Drawing;  
using System.Linq;  
using System.Text;  
using System.Threading.Tasks;  
using System.Windows.Forms;  
  
namespace Extract  
{  
    public partial class TimeCounter : Label  
    {  
        private Timer _timer;  
        private int _elapsedSeconds;  
  
        public TimeCounter()  
        {  
            InitializeComponent();  
  
            _timer = new Timer  
            {  
                Interval = 1000,  
                Enabled = true  
            };  
            _timer.Tick += (sender, args) =>  
            {  
                _elapsedSeconds++;  
                TimeSpan time = TimeSpan.FromSeconds(_elapsedSeconds);  
                this.Text = time.ToString(@"hh\:mm\:ss");  
            };  
        }  
  
        private void TimeCounter_Load(object sender, EventArgs e)  
        {  
  
        }  
    }  
}  

I tried to change the line _elapsedSeconds++; to _elapsedSeconds--; but it's keep counting up. I want to be able to change the counter either to count down or up.

Answer 1

In the following example, the Timer was dropped from the ToolBox.

using System;
using System.Windows.Forms;

namespace TimerUpDown
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private bool _direction;
        private int _seconds;
        private int _highValue = 10;
        private int _lowValue = 0;

        private void button1_Click(object sender, EventArgs e)
        {
            timer1.Enabled = false;
            _direction = checkBox1.Checked;
            _seconds = _direction ? _lowValue : _highValue;
            timer1.Enabled = true;
        }
        private void timer1_Tick(object sender, EventArgs e)
        {
            if (_direction)
            {
                _seconds++;
            }
            else
            {
                _seconds--;
            }

            label1.Text = TimeSpan.FromSeconds(_seconds).ToString("mm\\:ss");

            if (_seconds == _lowValue || _seconds >= _highValue)
            {
                timer1.Enabled = false;
            }

        }
    }
}