private void button1_Click(object sender, EventArgs e)
  {
   double op1, op2, result;
   if (textBox1.Text == ""||textBox2.Text=="" ) {//判斷是否兩個框框都輸入了數(shù)據(jù)
    MessageBox.Show(this,"輸入錯誤","msg",MessageBoxButtons.OK,
     MessageBoxIcon.Information);//有空余項沒輸入數(shù)據(jù)彈出提示框
    return;
   }
   op1 = double.Parse(textBox1.Text);//得到兩個框框的值并轉化為long類型
   op2 = double.Parse(textBox2.Text);

   if (radioButton1.Checked) {//加法
    result = op1 + op2;
   }
   else if (radioButton2.Checked){//減法
    result = op1 - op2;
   }
   else if (radioButton3.Checked){//乘法
    result = op1 * op2;
   }
   else {//除法
    result = op1 / op2;
   }
   textBox3.Text = result.ToString();//設置textBox3的值
  }