【问题标题】：C# Looping Messagebox for Exception异常的 C# 循环消息框
【发布时间】：2016-04-12 19:14:38
【问题描述】：

循环消息框！！

发生错误后我有一个循环消息框，我想知道如何修复它。我尝试返回 Calculate() 方法，我认为这是问题所在，但我不确定。

namespace WindowsFormsApplication7
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        public int division = 0;
        private void Form1_Load(object sender, EventArgs e)
        {

        }
        private decimal Calculate()
        {
            // This array is to hold the logical operators
            string[] allowed = { "+", "-", "*", "/" };

            // If the right operator is selceted then perform the action and return result
            if (operate.Text == "+")
            {
                decimal division = Convert.ToDecimal(operand1.Text) + Convert.ToDecimal(operand2.Text);                
            }
            else if (operate.Text == "-")
            {
                decimal division = Convert.ToDecimal(operand1.Text) - Convert.ToDecimal(operand2.Text);
            }
            else if (operate.Text == "*")
            {
                decimal division = Convert.ToDecimal(operand1.Text) * Convert.ToDecimal(operand2.Text);
            }
            else if (operate.Text == "/")
            {
                decimal division = (Convert.ToDecimal(operand1.Text) / Convert.ToDecimal(operand2.Text));             
            }
            // if the operator is not something within the array then display message
            else if (!allowed.Contains(operate.Text))
            {
                string msg = string.Format("Not a valid operater {0}Please Enter one of the Following:{0}{1}"
                , Environment.NewLine, string.Join(Environment.NewLine, allowed));
                MessageBox.Show(msg);
                operate.Text = "";             
            }
            return Calculate();
        }

【问题讨论】：

您需要在方法顶部声明 division 并在底部返回。
return Calculate(); 永远递归调用函数，

标签： c# loops methods messagebox

【解决方案1】：

试试

private decimal Calculate()
{
     // This array is to hold the logical operators
     string[] allowed = { "+", "-", "*", "/" };

     decimal result = 0m;
     // If the right operator is selected then perform the action and return result
     if (operate.Text == "+")
     {
          result = Convert.ToDecimal(operand1.Text) + Convert.ToDecimal(operand2.Text);                
     }
     else if (operate.Text == "-")
     {
          result = Convert.ToDecimal(operand1.Text) - Convert.ToDecimal(operand2.Text);
      }
      else if (operate.Text == "*")
      {
          result = Convert.ToDecimal(operand1.Text) * Convert.ToDecimal(operand2.Text);
      }
      else if (operate.Text == "/")
      {
          result  = (Convert.ToDecimal(operand1.Text) / Convert.ToDecimal(operand2.Text));             
      }
      // if the operator is not something within the array then display message
      else if (!allowed.Contains(operate.Text))
      {
          string msg = string.Format("Not a valid operater {0}Please Enter one of the Following:{0}{1}"
        , Environment.NewLine, string.Join(Environment.NewLine, allowed));

          MessageBox.Show(msg);

          operate.Text = "";

      }

    return result;

}

【讨论】：

【解决方案2】：

// 试试这个

        private void button1_Click(object sender, EventArgs e)
        {
           result.Text = Calculate().ToString();
        }


        private decimal Calculate() {

            decimal division = 0;

            // This array is to hold the logical operators
        string[] allowed = { "+", "-", "*", "/" };

            // If the right operator is selceted then perform the action and return result
            if (operate.Text == "+")
            {
                 division = Convert.ToDecimal(operand1.Text) + Convert.ToDecimal(operand2.Text);
    }
            else if (operate.Text == "-")
            {
                 division = Convert.ToDecimal(operand1.Text) - Convert.ToDecimal(operand2.Text);
}
            else if (operate.Text == "*")
            {
                 division = Convert.ToDecimal(operand1.Text) * Convert.ToDecimal(operand2.Text);
            }
            else if (operate.Text == "/")
            {
                 division = (Convert.ToDecimal(operand1.Text) / Convert.ToDecimal(operand2.Text));
            }
            // if the operator is not something within the array then display message
            else if (!allowed.Contains(operate.Text))
            {
                string msg = string.Format("Not a valid operater {0}Please Enter one of the Following:{0}{1}"
                , Environment.NewLine, string.Join(Environment.NewLine, allowed));
MessageBox.Show(msg);
                operate.Text = "";
            }
            return division;
        }

    }

【讨论】：