// 构造函数里
this.button1.Text = "0";

// 点击事件
private void button1_Click(object sender, EventArgs e)
{
    this.button1.Text = (int.Parse(this.button1.Text) + 1).ToString();
}

------解决方案--------------------
设置一个全局变量咯，
int click_count=0;
private void button1_Click(object sender, EventArgs e)
       {
         click_count++;
       }

private void button2_Click(object sender, EventArgs e)
       {
         click_count=0      
  }

------解决方案--------------------
C# code

        static int count = 0;
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {

            count++;
        }

        private void button2_Click(object sender, EventArgs e)
        {
            count = 0;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            MessageBox.Show(count.ToString());
        }

------解决方案--------------------
不显示在按钮上
C# code
// 全局变量
private int clickCount = 0;

// 递增按钮事件
private void button1_Click(object sender, EventArgs e)
{
    ++clickCount;
}

// 清空按钮事件
private void button1_Click(object sender, EventArgs e)
{
    clickCount = 0;
}

------解决方案--------------------
C# code

        public Form1()
        {
            InitializeComponent();
            button1.Tag = 0;
        }
        private void button1_Click(object sender, EventArgs e)
        {
            button1.Tag = Convert.ToInt32(button1.Tag) + 1;
        }

        private void button2_Click(object sender, EventArgs e)
        {
            button1.Tag = 0;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            MessageBox.Show(button1.Tag.ToString());
        }