c# - 降序数字 C#

Question

我能够编写此程序的这一小段以按升序显示数字，但我仍然无法让它按降序显示。

该程序的基本操作是以“From”和“To”的形式从用户那里获取两个数值，并将其显示为列表框中的列表。用户选择升序还是降序取决于他选择了两个单选按钮中的哪一个。

    private void btnCalc_Click(object sender, EventArgs e)
    {

        double fromNum, toNum, total = 0;

        fromNum = double.Parse(txtFrom.Text);
        toNum = double.Parse(txtTo.Text);

        lstResult.Items.Clear();
        lblResult.Text = "";

        if (radAsc.Checked)
        {
            while (fromNum <= toNum)
            {
                lstResult.Items.Add(fromNum);

                total = total + fromNum;

                fromNum++;
            }
        }

        else
        {
            while (fromNum >= toNum)
            {
                lstResult.Items.Add(fromNum);

                total = total + toNum;

                toNum--;
            }
        }

        lblResult.Text = total.ToString();
    }

这是该程序的外观图片。 http://imgur.com/SVwN3Tx

注意:- 我是 C# 的新手，刚开始在大学学习。

Answer 1

我建议使用 for 循环而不是 while 这使得代码易于实现:

    if (radAsc.Checked)
    {
        // num += 1: - I've seen odds/even switch on the screenshot
        // so you may want to change/add num += 1 into num += 2
        for (double num = fromNum; num <= toNum; num += 1) {
          lstResult.Items.Add(num);
          total = total + num;
        }
    }
    else
    {
        // Descending order: 
        //   - start from the bottom (toNum)
        //   - loop until the top (fromNum) 
        //   - descend by 1 (num -= 1)
        for (double num = toNum; num >= fromNum; num -= 1) {
          lstResult.Items.Add(num);
          total = total + num;
        }
    }