Question

我想将文本框中的元素添加到数组中，但每次尝试添加名称时都会抛出异常。我想在点击按钮后添加元素。

   private void Grade_Click(object sender, EventArgs e)
        {
            string name;
            double grade;


            nametextbox.Text = "";
            gradetextbox.Text = "";

           for (int i = 0; i < 10; i++)
           {
            grade = Convert.ToDouble(gradetextbox.Text);
            grades[i] += grade;



            name = nametextbox.Text;
            names[i] += name;
        }


    }

Answer 1

你这样做：

gradetextbox.Text = "";

将Text属性设置为空字符串。然后你这样做：

grade = Convert.ToDouble(gradetextbox.Text);

试图将空字符串转换为double，这显然不起作用，因此会引发异常。

你可能需要的是：

private double[] grades = new double[10]; // 10 grades
private string[] names = new string[10]; // 10 names
private int currentIndex = 0;
private void Grade_Click(object sender, EventArgs e)
{
    if (currentIndex > 10)
    {
        MessageBox.Show("No more enteries allowed");
    }

    string name;
    double grade;

    if (double.TryParse(gradetextbox.Text, out grade))
    {
        grades[currentIndex] += grade;
    }
    else
    {
        MessageBox.Show("Grade enterd is not a valid grade");
        return;// do nothing else
    }

    name = nametextbox.Text;
    names[i] += name;

    // now clear the textboxes so user can enter another value
    nametextbox.Text = "";
    gradetextbox.Text = "";
    currentIndex = currentIndex + 1;
}

从两个文本框中获取文本并将元素添加到数组中

1 个答案: