Question

在我的计算行中，我得到错误“使用未分配的局部变量...”，用于提交住宿费，注册费和天数。我已经在开始时声明了变量，所以我不知道我应该做什么。

private void button1_Click(object sender, EventArgs e)
    {
        decimal days;
        decimal registrationFee;
        decimal lodgingFee;
        decimal total;
        decimal lodgingCal;

        string registration;

        if (workshopListBox.SelectedIndex != -1)
        {
            registration = workshopListBox.SelectedItem.ToString();

            switch (registration)
            {
                case "Handling Stress":
                    registrationTextBox.Text = "$1000";
                    days = 3;
                    registrationFee = 1000;
                    break;
                case "Time Managment":
                    registrationTextBox.Text = "$800";
                    days = 3;
                    registrationFee = 800;
                    break;
                case "Supervision Skills":
                    registrationTextBox.Text = "$1500";
                    days = 3;
                    registrationFee = 1500;
                    break;
                case "Negotiation":
                    registrationTextBox.Text = "$1300";
                    days = 5;
                    registrationFee = 1300;
                    break;
                case "How to Interview":
                    registrationTextBox.Text = "$500";
                    days = 1;
                    registrationFee = 500;
                    break;
            }
        }

        string lodging;

        if (locationListBox.SelectedIndex != -1)
        {
            lodging = locationListBox.SelectedItem.ToString();

            switch (lodging)
            {
                case  "Austin":
                    lodgingTextBox.Text = "$150";
                    lodgingFee = 150;
                    break;
                case "Chicago":
                    lodgingTextBox.Text = "$225";
                    lodgingFee = 225;
                    break;
                case "Dallas":
                    lodgingTextBox.Text = "$175";
                    lodgingFee = 175;
                    break;
                case "Orlando":
                    lodgingTextBox.Text = "$300";
                    lodgingFee = 300;
                    break;
                case "Phoenix":
                    lodgingTextBox.Text = "$175";
                    lodgingFee = 175;
                    break;
                case "Raleigh":
                    lodgingTextBox.Text = "$150";
                    lodgingFee = 150;
                    break;
            }
        }

        lodgingCal = lodgingFee * days;
        total = registrationFee + lodgingCal;


        totalTextBox.Text = total.ToString("c");

     }

    }
}

Answer 1

您必须在使用它们之前初始化变量。

decimal days = 0.0;
decimal registrationFee = 0.0;
decimal lodgingFee =0.0;
decimal total = 0.0;
decimal lodgingCal= 0.0;

Answer 2

在switch语句中添加一个默认大小写，您可以在其中引发异常或为这些变量分配一些错误值。

switch (registration)
        {
            case "Handling Stress":
                registrationTextBox.Text = "$1000";
                days = 3;
                registrationFee = 1000;
                break;
            case "Time Managment":
                registrationTextBox.Text = "$800";
                days = 3;
                registrationFee = 800;
                break;
            case "Supervision Skills":
                registrationTextBox.Text = "$1500";
                days = 3;
                registrationFee = 1500;
                break;
            case "Negotiation":
                registrationTextBox.Text = "$1300";
                days = 5;
                registrationFee = 1300;
                break;
            case "How to Interview":
                registrationTextBox.Text = "$500";
                days = 1;
                registrationFee = 500;
                break;
            default:
                throw new ApplicationException("oh no I don't want this");
        }

您收到错误是因为代码中可能存在执行路径，即使尚未分配变量，您也已经在使用它们。这只能在您不处理注册的情况下进行，这就是为什么最好在所有switch语句中添加默认值。这是防御性的编程。

Answer 3

您必须手动初始化局部变量，因为它默认情况下不会初始化。

您应该在使用之前初始化变量lodgingFee。你应该看起来像下面的代码。

private void button1_Click(object sender, EventArgs e)
    {
        decimal days = 0.0;
        decimal registrationFee = 0.0;
        decimal lodgingFee = 0.0;
        decimal total = 0.0;
        decimal lodgingCal = 0.0;
        string registration = "";
        ...............
        ...................
    }

Answer 4

为每个变量分配一些默认值。

    private void button1_Click(object sender, EventArgs e)
    {
        decimal days = 0.0;
        decimal registrationFee = 0.0;
        decimal lodgingFee = 0.0;
        decimal total = 0.0;
        decimal lodgingCal = 0.0;

        string registration = String.Empty;
        //..............
    }

怎么处理我的错误？

4 个答案: