Question

以下功能在此行无法正常工作

if (itemDescription.ToLower().Contains(txtComKeyword1.Text.ToLower()) ||
    itemDescription.ToLower().Contains(txtComKeyword2.Text.ToLower()) ||
    itemDescription.ToLower().Contains(txtComKeyword3.Text.ToLower()) ||
    itemDescription.ToLower().Contains(txtComKeyword4.Text.ToLower()))

如果txtComKeyword中的一个/多个为空。它只有在填充了txtComKeyword的所有四个时才能正常工作。

我希望通过使用关键字限制来过滤XML文件的数据。 <item></item>中检测到哪些关键字将作为结果显示。我想允许用户选择是否只输入一个/两个/三个/四个关键字。不幸的是，只要空txtComKeywords，就会输出整个XML文件的<item></item>。

我对编程非常陌生。如果有可能，请各位帮忙吗？谢谢。

我的代码：

private void searchComByKeywords()
{
    // Process the list of files found in the directory. 
    string[] fileEntries = Directory.GetFiles(sourceDir);
    foreach (string fileName in fileEntries)
    {
        try
        {
            XmlDocument xmlDoc = new XmlDocument(); //* create an xml document object.

            string docPath = fileName;

            xmlDoc.Load(docPath); //* load the XML document from the specified file.

            XmlNodeList nodeList = xmlDoc.GetElementsByTagName("item");

            foreach (XmlNode node in nodeList)
            {

                XmlElement itemElement = (XmlElement) node;

                string itemDescription = itemElement.GetElementsByTagName("description")[0].InnerText;

                if (itemDescription.ToLower().Contains(txtComKeyword1.Text.ToLower()) || itemDescription.ToLower().Contains(txtComKeyword2.Text.ToLower()) || itemDescription.ToLower().Contains(txtComKeyword3.Text.ToLower()) || itemDescription.ToLower().Contains(txtComKeyword4.Text.ToLower()))
                {
                    string itemTitle = itemElement.GetElementsByTagName("title")[0].InnerText;
                    string itemDate = itemElement.GetElementsByTagName("pubDate")[0].InnerText;
                    string itemAuthor = itemElement.GetElementsByTagName("author")[0].InnerText;

                    richComResults.AppendText("Author: " + itemAuthor + "\nDate: " + itemDate + "\nTitle: " + itemTitle + "\nDescription: " + itemDescription + "\n\n--------\n\n");
                }
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }
}

编辑：

private void searchComByKeywords()
{
    // Process the list of files found in the directory. 
    string[] fileEntries = Directory.GetFiles(sourceDir);
    foreach (string fileName in fileEntries)
    {
        try
        {
            XmlDocument xmlDoc = new XmlDocument(); //* create an xml document object.

            string docPath = fileName;

            xmlDoc.Load(docPath); //* load the XML document from the specified file.

            XmlNodeList nodeList = xmlDoc.GetElementsByTagName("item");

            foreach (XmlNode node in nodeList)
            {

                XmlElement itemElement = (XmlElement) node;
                string itemDescription = itemElement.GetElementsByTagName("description")[0].InnerText;
                string[] words = new String[] { null, null, null, null };
                string key1 = txtComKeyword1.Text.Trim();
                string key2 = txtComKeyword2.Text.Trim();
                string key3 = txtComKeyword3.Text.Trim();
                string key4 = txtComKeyword4.Text.Trim();
                words[0] = (key1.Length == 0 ? null : key1.ToLower());
                words[1] = (key2.Length == 0 ? null : key2.ToLower());
                words[2] = (key3.Length == 0 ? null : key3.ToLower());
                words[3] = (key4.Length == 0 ? null : key4.ToLower());

                if (words.Contains(itemDescription.ToLower())) 
                {
                    string itemTitle = itemElement.GetElementsByTagName("title")[0].InnerText;
                    string itemDate = itemElement.GetElementsByTagName("pubDate")[0].InnerText;
                    string itemAuthor = itemElement.GetElementsByTagName("author")[0].InnerText;

                    richComResults.AppendText("Author: " + itemAuthor + "\nDate: " + itemDate + "\nTitle: " + itemTitle + "\nDescription: " + itemDescription + "\n\n--------\n\n");
                }
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }
}

Answer 1

在进入循环之前阅读所有单词并将其保存在字符串数组中在输入数组中的单词之前，检查文本框是否为空然后使用 Array.Contains 方法检查itemDescription是否在单词数组中

string[] words = new String[] {null, null, null, null};
// as from John Saunders comment below, 
// pass everything into a local temp variable to avoid double 
// evaluation (and string rebuild) of the Trim() method
string key1 = txtComKeyword1.Text.Trim();
string key2 = txtComKeyword2.Text.Trim();
string key3 = txtComKeyword3.Text.Trim();
string key4 = txtComKeyword4.Text.Trim();
words[0] = (key1.Length == 0 ? null : key1.ToLower());
words[1] = (key2.Length == 0 ? null : key2.ToLower());
words[2] = (key3.Length == 0 ? null : key3.ToLower());
words[3] = (key4.Length == 0 ? null : key4.ToLower());

if (words.Contains(itemDescription.ToLower())) 
    .....

优点是双重的：

您只读了一次textBox并转换为小写循环
if语句非常简化

C＃中的ternary operator是表达通用编码模式的更简单方法

if(condition == true)
   variable = first statement;
else
   variable = second statement;

该代码变为三元运算符

   variable = (condition == true ? first statement : second statement);

当包含的一个/多个关键字为空时，输出不会被过滤

1 个答案: