异常使用TryCatch

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一个小例子，展示try catch的强大

1.一个输入框，只允许输入数字，当输入不是数字时，进行警告提示。

2. 使用 keyup事件：（最后发生，一次键盘敲入事件彻底完成）

3. try catch 代码

 /// <summary>
        /// 
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void tbNum_KeyUp(object sender, KeyEventArgs e)
        {
             strVal = this.txtNum.Text;
            try
            {
                int iNum = Convert.ToInt32(strVal);
            }
            catch (Exception)
            {
                this.txtNum.Text = "";
                MessageBox.Show("只能输入数字");
            }
        }

4. 按钮监听返回值

5. 页面代码

 public FormBianNo()
        {
            InitializeComponent();
        }

        public string strBianNo = "";


        /// <summary>
        /// 
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void tbNum_KeyUp(object sender, KeyEventArgs e)
        {
             strVal = this.txtNum.Text;
            try
            {
                int iNum = Convert.ToInt32(strVal);
            }
            catch (Exception)
            {
                this.txtNum.Text = "";
                MessageBox.Show("只能输入数字");
            }
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnOk_Click(object sender, EventArgs e)
        {
            if (strVal != "")
            {
                strBianNo = txtNum.Text;
                MessageBox.Show("编号添加成功");
            }
            else
            {
                MessageBox.Show("未输入编号");
            }
            
        }

        private void btnCancel_Click(object sender, EventArgs e)
        {
            FormBianNo fbn = new FormBianNo();
            fbn.Close();
        }