Question

如果用户键入负利率，我需要有一个基本错误捕获产生错误声明。目前我有这个贷款计算器产生关于负利率的错误，但它在if else声明中。我也有一个try catch语句，但是如果用户输入的数字不是数字，它只会产生错误信息。关于如何使用try catch语句的任何指示/提示都会产生我的负利率错误。谢谢

namespace Program_3_Car_Calc
{
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e) // Calculate message box 
    {
        double LoanAmount = 0;
        double Payment = 0;
        double InterestRate = 0;
        double DownPayment = 0;
        int PaymentPeriods = 0;

        // Inputs
        try
        {
            InterestRate = Convert.ToDouble(txtRate.Text);
            PaymentPeriods = Convert.ToInt16(Convert.ToDouble(txtTime.Text) * 12);
            LoanAmount = Convert.ToDouble(txtLoan.Text);
            DownPayment = Convert.ToDouble(txtDown.Text);

            // Calculate the monthly payment 
            if (InterestRate > 0)
            {
                InterestRate = InterestRate / 100;
            }

            else
            {
                MessageBox.Show("Error, Please enter a positive number");
            }

            Payment = ((LoanAmount - DownPayment) * Math.Pow((InterestRate / 12) + 1,
           (PaymentPeriods)) * InterestRate / 12) / (Math.Pow(InterestRate / 12 + 1,
           (PaymentPeriods)) - 1);
           Payment = Math.Round(Payment, 2);

            // Ouptput the results of the monthly payment 
            lblMonthlyPayment.Text = "Your Monthly Payment will be: " + "$" + Payment.ToString   ("N2");

        }
        catch
        {
            MessageBox.Show("You have entered an invalid character");
        }


    }
    private void CloseGoodbye(string message, string title = " ", int amount = 0) //Optional Parameter for amount of time message box appears 
    {
        for (int i = 0; i < amount; i++)
        MessageBox.Show(message, title);
        Application.Exit();
    }

    private void cmdFinished_Click(object sender, EventArgs e) // Finished Message box 
    {
        CloseGoodbye("Goodbye", "Loan Calc", 1);
    }


}

Answer 1

我的建议是坚持使用if / else声明。

避免使用try / catch来捕获可预防的错误。这不是最佳做法。

如果你因为抛出异常而死定，那么你可以输入

throw new ArgumentException("You have entered an invalid character");

您可以在技术上抛出任何类型的异常，但ArguementException通常用于有无效参数时。

请记住，如果您立即捕获此异常，则异常的整个目的都将丢失

C＃中捕获的基本错误

1 个答案: