2

我创建了一个程序，并对其进行了广泛的测试，我收到一条错误消息，提示“未处理 FormatException，输入字符串的格式不正确”。当我将任一文本框留空并按下“完成”按钮时会出现问题，但如果我输入低于 0 或高于 59 的任何内容（这是我想要允许的数字范围），它工作正常。当框为空白时，我该怎么做才能不收到此错误？这是我在“btnFinished”后面的代码：

   private void btnFinished_Click(object sender, EventArgs e)
    {
        if (lstCyclists.SelectedIndex >= 0)
        {
            Cyclists currentCyc = (Cyclists)lstCyclists.SelectedItem;
            //Decalre the minsEntered and secsEntered variables for txtMins and textSecs
            int minsEntered = int.Parse(txtMins.Text);
            int secsEntered = int.Parse(txtSecs.Text);

            try
            {
                //If the status of a cyclist is already set to Finished, show an error
                if (currentCyc.Finished.ToString() == "Finished")
                {
                    MessageBox.Show("A time has already been entered for this cyclist");
                }
                else
                {
                    //if a minute lower than 0 or greater than 59 has been entered, show an error
                    if (minsEntered < 0 || minsEntered > 59)
                    {
                        MessageBox.Show("You can only enter a minute up to 59");
                    }
                    //if a second lower than 0 or greater than 59 has been entered, show an error
                    else if (secsEntered < 0 || secsEntered > 59)
                    {
                        MessageBox.Show("You can only enter a second up to 59");
                    }
                    else
                    {
                        //otherwise, set the status to finished and update the time
                        currentCyc.Finished = "Finished";
                        currentCyc.FinishedHours(Convert.ToInt32(txtHours.Text));
                        currentCyc.FinishedMins(Convert.ToInt32(txtMins.Text));
                        currentCyc.FinishedSecs(Convert.ToInt32(txtSecs.Text));
                        //pass the parameter to the scoreboard class to display it in lblCyclistsFinished
                        lblCyclistsFinished.Text += "\n" + finishLine.Scoreboard(currentCyc);
                        //add to the number of cyclists finished
                        Cyclists.NumFinished++;
                        lblnumFinished.Text = Cyclists.NumFinished.ToString();
                        //update the details box
                        DisplayDetails(currentCyc);
                        txtHours.Clear();
                    }
                }
            }
            catch
            //make sure all the time fields have been entered, otherwise show an error message
            {
                MessageBox.Show("Please ensure all time fields have been entered");
            }
        }
        else
            //make sure a cyclist has been selected when pressing "Finished", otherwise show an error message
        {
            MessageBox.Show("You must select a cyclist");
        }
    }
4

3 回答 3

8

好吧，看看这些行：

int minsEntered = int.Parse(txtMins.Text);
int secsEntered = int.Parse(txtSecs.Text);

当文本框为空白时，您希望那些返回什么？

根本不要求int.Parse空文本框。例如：

int minsEntered = txtMins.Text == "" ? 0 : int.Parse(txtMins.Text);
// Ditto for seconds

当然，如果您输入非数字的内容，这仍然会爆炸。您可能应该int.TryParse改用：

int minsEntered;
int.TryParse(txtMins.Text, out minsEntered);

在这里，我忽略了 的结果TryParse，无论如何它都会保留minsEntered为 0 - 但如果你想要一个不同的默认值，你会使用类似的东西：

int minsEntered;
if (!int.TryParse(txtMins.Text, out minsEntered))
{
    minsEntered = 5; // Default on parsing failure
}

（或者您可以在这种情况下显示错误消息...）

于 2012-11-09T16:54:06.957 回答
3

当我将任一文本框留空时会出现问题

这就是问题所在。您正在使用int.Parse空字符串。空字符串不是有效的整数表示，解析失败。

您可以测试文本框中的值并默认为合理的值：

int minsEntered = 0;
int secsEntered = 0;

if(!string.IsNullOrWhitespace(textMins.Text))
{
  minsEntered = int.Parse(txtMins.Text);
}

if(!string.IsNullOrWhitespace(txtSecs.Text))
{
  secsEntered = int.Parse(txtSecs.Text);
}
于 2012-11-09T16:53:19.890 回答
2

您可以使用 int.TryParse，它返回一个布尔值来指示文本是否解析成功：

int minsEntered = 0;
if (int.TryParse(txtMins.Text, out minsEntered))
{
    // txtMins.Text is a valid integer.
}
于 2012-11-09T16:59:23.750 回答