Linq to XML - 更新/更改 XML 文档的节点答案

【问题标题】：Linq to XML - update/alter the nodes of an XML DocumentLinq to XML - 更新/更改 XML 文档的节点
【发布时间】：2010-09-24 19:04:28
【问题描述】：

我有 2 个问题：

1。我已经开始使用 Linq to XML，我想知道是否可以通过 Linq 更改 XML 文档。我的意思是，有没有类似的东西

XDocument xmlDoc = XDocument.Load("sample.xml");

update item in xmlDoc.Descendants("item")
where (int)item .Attribute("id") == id
...

2。我已经知道如何通过简单地使用来创建和添加新的 XMLElement

xmlDoc.Element("items").Add(new XElement(......);

但是如何删除单个条目？

XML 示例数据：

<items>
  <item id="1" name="sample1" info="sample1 info" web="" />
  <item id="2" name="sample2" info="sample2 info" web="" />
</itmes>

【问题讨论】：

标签： c# xml linq linq-to-xml

【解决方案1】：

感谢您的回答。一切正常。

正如我的问题的补充，下面的代码显示了如何修改单个条目：

string xml = @"<data><record id='1' info='sample Info'/><record id='2' info='sample Info'/><record id='3' info='sample Info'/></data>";
StringReader sr = new StringReader(xml);
XDocument d = XDocument.Load(sr);


d.Descendants("record").Where(x => x.Attribute("id").Value == "2").Single().SetAttributeValue("info", "new sample info");

【讨论】：

仅供参考：您可以跳过 StringReader 步骤，直接说 XDocument d = XDocument.Parse(xml)。

【解决方案2】：

这是你的想法吗？

using System;
using System.Linq;
using System.Xml.Linq;

static void Main(string[] args)
{
    string xml = @"<data><record id='1'/><record id='2'/><record id='3'/></data>";
    StringReader sr = new StringReader(xml);
    XDocument d = XDocument.Load(sr);

    // the verbose way, if you will be removing many elements (though in
    // this case, we're only removing one)
    var list = from XElement e in d.Descendants("record")
               where e.Attribute("id").Value == "2" 
               select e;

    // convert the list to an array so that we're not modifying the
    // collection that we're iterating over
    foreach (XElement e in list.ToArray())
    {
       e.Remove();
    }

    // the concise way, which only works if you're removing a single element
    // (and will blow up if the element isn't found)
    d.Descendants("record").Where(x => x.Attribute("id").Value == "3").Single().Remove();

    XmlWriter xw = XmlWriter.Create(Console.Out);
    d.WriteTo(xw);
    xw.Flush();
    Console.ReadLine();
}

【讨论】：

@Robert，我们必须在代码中包含什么以确保它不会爆炸？谢谢。
这就是简洁方法之上的详细方法的用途：如果您构建列表然后对其进行迭代，如果列表为空，代码将起作用。
@Robert，无需通读 Stream，XDocument.Parse(xmlString) 即可。

【解决方案3】：

答案在这个帖子中......你只需要做很多排序才能找到它们，所以我已经为你完成了编译它们的工作：

是的，您可以编辑元素
删除元素很简单：element.Remove(); （之后记得保存 xDocument）

现在，如果您正在阅读此主题，您可能想知道如何编辑元素。在 xml 中存储数据有两种不同的方式，例如：

<tagName attributeName="some value">another value</tagName>

作为标签上的属性
作为标签的内容（读取值）

要编辑属性的值，knox 回答了他自己的问题：

d.Descendants("record").Where(x => x.Attribute("id").Value == "2").Single().SetAttributeValue("info", "new sample info");

也就是说，获取你想要改变的XElement，然后调用element.SetAttributeValue("AttributeName", "new value for the attribute")

如果你想编辑标签的值或内容，那么 Ajay 回答了它（如果你仔细研究了他的所有代码）：

persondata.Element("City").Value = txtCity.Text;

或者，换句话说，一旦你拥有你所追求的 XElement，只需使用 .Value 并分配出去。

请记住，在对内存中的元素执行任何这些修改后，如果要将这些更改保存到磁盘，则必须在 XDocument 上调用 .Save()。

【讨论】：

【解决方案4】：

使用系统；使用 System.Collections.Generic；使用 System.Linq；使用 System.Text；使用 System.Xml.Linq； //使用 System.Xml;

命名空间 XMLtoLinqApp { 课堂节目 { 静态无效主要（字符串 [] 参数） {

        //XmlDocument doc = new XmlDocument();
        //XmlElement newBook=doc.CreateElement("BookParticipant");
        //newBook.SetAttribute("Author");

        //Using Functional Construction to Create an XML Schema
        XElement xBookParticipant = new XElement("BookParticipant",
                                        new XElement("FirstName", "Joe"),
                                        new XElement("LastName", "Rattz"));
        Console.WriteLine(xBookParticipant.ToString());


        //Creates the Same XML Tree as Listing 6-1 but with Far Less Code
        XElement xBookParticipants = new XElement("BookParticipants",
                                        new XElement("BookParticipant",
                                        new XAttribute("type", "Author"),
                                        new XElement("FirstName", "Joe"),
                                        new XElement("LastName", "Rattz")),
                                        new XElement("BookParticipant",
                                        new XAttribute("type", "Editor"),
                                        new XElement("FirstName", "Ewan"),
                                        new XElement("LastName", "Buckingham")));
        Console.WriteLine(xBookParticipants.ToString());


        //-- Disadvatages of XML document
        //System.Xml.XmlElement xmlBookParticipant = new System.Xml.XmlElement("BookParticipant");
        XElement xeBookParticipant = new XElement("BookParticipant");


        XDocument xDocument = new XDocument(new XElement("BookParticipants",
                                            new XElement("BookParticipant",
                                            new XAttribute("type", "Author"),
                                            new XElement("FirstName", "Joe"),
                                            new XElement("LastName", "Rattz"))));
        Console.WriteLine(xDocument.ToString());


        //--Calling the ToString Method on an Element Produces the XML Tree
        XElement name = new XElement("Name", "Joe");
        Console.WriteLine(name.ToString());

        //--Console.WriteLine Implicitly Calling the ToString Method on an Element to Produce an XML Tree


        XElement name1 = new XElement("Person",
                                      new XElement("FirstName", "Joe"),
                                      new XElement("LastName", "Rattz"));
        Console.WriteLine(name1);

        //-- Casting an Element to Its Value’s Data Type Outputs the Value
        Console.WriteLine(name);
        Console.WriteLine((string)name);

        //--Different Node Value Types Retrieved via Casting to the Node Value’s Type
        XElement count = new XElement("Count", 12);
        Console.WriteLine(count);
        Console.WriteLine((int)count);

        XElement smoker = new XElement("Smoker", false);
        Console.WriteLine(smoker);
        Console.WriteLine((bool)smoker);

        XElement pi = new XElement("Pi", 3.1415926535);
        Console.WriteLine(pi);
        Console.WriteLine((double)pi);


        DeferredQryProblem();


        GenerateXMlFromLinqQry();

        WithoutReaching();

        Ancestors();


        AncestorsAndSelf();

        SortSample();

        FindElementwithSpecificChild();

    }

    private static void DeferredQryProblem()
    {
        XDocument xDocument = new XDocument(
                    new XElement("BookParticipants",
                    new XElement("BookParticipant",
                    new XAttribute("type", "Author"),
                    new XElement("FirstName", "Joe"),
                    new XElement("LastName", "Rattz")),
                    new XElement("BookParticipant",
                    new XAttribute("type", "Editor"),
                    new XElement("FirstName", "Ewan"),
                    new XElement("LastName", "Buckingham"))));
        IEnumerable<XElement> elements =
        xDocument.Element("BookParticipants").Elements("BookParticipant");
        foreach (XElement element in elements)
        {
            Console.WriteLine("Source element: {0} : value = {1}",
            element.Name, element.Value);
        }
        foreach (XElement element in elements)
        {
            Console.WriteLine("Removing {0} = {1} ...", element.Name, element.Value);
            element.Remove();
        }
        Console.WriteLine(xDocument);


        foreach (XElement element in elements)
        {
            Console.WriteLine("Source element: {0} : value = {1}",
            element.Name, element.Value);
        }
        foreach (XElement element in elements.ToArray())
        {
            Console.WriteLine("Removing {0} = {1} ...", element.Name, element.Value);
            element.Remove();
        }
        Console.WriteLine(xDocument);
    }

    //-- Creating an Attribute and Adding It to Its Element
    private static void CreatingAttribute()
    {
        XElement xBookParticipant = new XElement("BookParticipant", new XAttribute("type", "Author"));
        Console.WriteLine(xBookParticipant);
    }

    //--Creating a Comment with Functional Construction
    private static void CreatingComment()
    {
        XElement xBookParticipant = new XElement("BookParticipant",
                                                  new XComment("This person is retired."));
        Console.WriteLine(xBookParticipant);
    }

    //--Creating a Declaration with Functional Construction
    private static void CreateXmlDeclaration()
    {
        XDocument xDocument = new XDocument(new XDeclaration("1.0", "UTF-8", "yes"),

new XElement("BookParticipant")); Console.WriteLine(xDocument); }

    private static void GenerateXMlFromLinqQry()
    {
        BookParticipant[] bookParticipants = new[] {new BookParticipant {FirstName = "Joe", LastName = "Rattz",
                                                    ParticipantType = ParticipantTypes.Author},
                                                    new BookParticipant {FirstName = "Ewan", LastName = "Buckingham",
                                                    ParticipantType = ParticipantTypes.Editor}
                                                    };
        XElement xBookParticipants =
        new XElement("BookParticipants",
                     bookParticipants.Select(p =>
                new XElement("BookParticipant",
                new XAttribute("type", p.ParticipantType),
                new XElement("FirstName", p.FirstName),
                new XElement("LastName", p.LastName))));


        Console.WriteLine(xBookParticipants);
    }

    //-- Obtaining Elements Without Reaching
    private static void WithoutReaching()
    {
        XDocument xDocument = new XDocument(new XElement("BookParticipants",
                                            new XElement("BookParticipant",
                                            new XAttribute("type", "Author"),
                                            new XElement("FirstName", "Joe"),
                                            new XElement("LastName", "Rattz")),
                                            new XElement("BookParticipant",
                                            new XAttribute("type", "Editor"),
                                            new XElement("FirstName", "Ewan"),
                                            new XElement("LastName", "Buckingham"))));

        //-- Simple Descendants
        IEnumerable<XElement> elements = xDocument.Descendants("BookParticipant");


        foreach (XElement element in elements)
        {
            Console.WriteLine("Element: {0} : value = {1}",
            element.Name, element.Value);
        }


        //-- Descendants with Where Clause
        IEnumerable<XElement> elements1 = xDocument.Descendants("BookParticipant")
                                                   .Where(e => ((string)e.Element("FirstName")) == "Ewan");
        foreach (XElement element1 in elements1)
        {
            Console.WriteLine("Element: {0} : value = {1}",
            element1.Name, element1.Value);
        }

    }


    //-- Ancestors Prototype
    private static void Ancestors()
    {
        XDocument xDocument = new XDocument(new XElement("BookParticipants",
                                            new XElement("BookParticipant",
                                            new XAttribute("type", "Author"),
                                            new XElement("FirstName", "Joe"),
                                            new XElement("LastName", "Rattz")),
                                            new XElement("BookParticipant",
                                            new XAttribute("type", "Editor"),
                                            new XElement("FirstName", "Ewan"),
                                            new XElement("LastName", "Buckingham"))));

        IEnumerable<XElement> elements = xDocument.Element("BookParticipants").Descendants("FirstName");
        // First, I will display the source elements.
        foreach (XElement element in elements)
        {
            Console.WriteLine("Source element: {0} : value = {1}",
            element.Name, element.Value);
        }
        // Now, I will display the ancestor elements for each source element.
        foreach (XElement element in elements.Ancestors())
        {
            Console.WriteLine("Ancestor element: {0}", element.Name);
        }


        // Now, I will display the ancestor elements for each source element.
        foreach (XElement element in elements.Ancestors("BookParticipant"))
        {
            Console.WriteLine("Ancestor element: {0}", element.Name);
        }

    }


    //-- AncestorsAndSelf
    private static void AncestorsAndSelf()
    {
        XDocument xDocument = new XDocument(
            new XElement("BookParticipants",
            new XElement("BookParticipant",
            new XAttribute("type", "Author"),
            new XElement("FirstName", "Joe"),
            new XElement("LastName", "Rattz")),
            new XElement("BookParticipant",
            new XAttribute("type", "Editor"),
            new XElement("FirstName", "Ewan"),
            new XElement("LastName", "Buckingham"))));
        IEnumerable<XElement> elements =
        xDocument.Element("BookParticipants").Descendants("FirstName");
        // First, I will display the source elements.
        foreach (XElement element in elements)
        {
            Console.WriteLine("Source element: {0} : value = {1}",
            element.Name, element.Value);
        }
        // Now, I will display the ancestor elements for each source element.
        foreach (XElement element in elements.AncestorsAndSelf())
        {
            Console.WriteLine("Ancestor element: {0}", element.Name);
        }


        // Now, I will display the ancestor elements for each source element.
        foreach (XElement element in elements.AncestorsAndSelf("BookParticipant"))
        {
            Console.WriteLine("Ancestor element: {0}", element.Name);
        }

    }


    //-- Sort Smaple

    private static void SortSample()
    {
        XElement root = XElement.Load("Data.xml");
        IEnumerable<decimal> prices =
            from el in root.Elements("Data")
            let price = (decimal)el.Element("Price")
            orderby price
            select price;
        foreach (decimal el in prices)
            Console.WriteLine(el);
    }

    //-- Find an Element with a Specific Child 
    private static void FindElementwithSpecificChild()
    {
        XElement root = XElement.Load("data.xml");
        IEnumerable<XElement> tests =
            from el in root.Elements("Data")
            where (int)el.Element("Quantity") > 3
            select el;
        foreach (XElement el in tests)
            Console.WriteLine((string)el.Attribute("TestId");
    }
}

}

http://msdn.microsoft.com/en-us/library/bb387053.aspx

7.25--> 一种 3 24.50 乙 1 89.99 一种 5 4.95 一种 3 66.00 乙 10 .99 一种 15 29.00 乙 8 6.99

【讨论】：

【解决方案5】：

static void Main(string[] args)
    {

        //XmlDocument doc = new XmlDocument();
        //XmlElement newBook=doc.CreateElement("BookParticipant");
        //newBook.SetAttribute("Author");

        //Using Functional Construction to Create an XML Schema
        XElement xBookParticipant = new XElement("BookParticipant",
                                        new XElement("FirstName", "Joe"),
                                        new XElement("LastName", "Rattz"));
        Console.WriteLine(xBookParticipant.ToString());


        //Creates the Same XML Tree as Listing 6-1 but with Far Less Code
        XElement xBookParticipants = new XElement("BookParticipants",
                                        new XElement("BookParticipant",
                                        new XAttribute("type", "Author"),
                                        new XElement("FirstName", "Joe"),
                                        new XElement("LastName", "Rattz")),
                                        new XElement("BookParticipant",
                                        new XAttribute("type", "Editor"),
                                        new XElement("FirstName", "Ewan"),
                                        new XElement("LastName", "Buckingham")));
        Console.WriteLine(xBookParticipants.ToString());


        //-- Disadvatages of XML document
        //System.Xml.XmlElement xmlBookParticipant = new System.Xml.XmlElement("BookParticipant");
        XElement xeBookParticipant = new XElement("BookParticipant");


        XDocument xDocument = new XDocument(new XElement("BookParticipants",
                                            new XElement("BookParticipant",
                                            new XAttribute("type", "Author"),
                                            new XElement("FirstName", "Joe"),
                                            new XElement("LastName", "Rattz"))));
        Console.WriteLine(xDocument.ToString());


        //--Calling the ToString Method on an Element Produces the XML Tree
        XElement name = new XElement("Name", "Joe");
        Console.WriteLine(name.ToString());

        //--Console.WriteLine Implicitly Calling the ToString Method on an Element to Produce an XML Tree


        XElement name1 = new XElement("Person",
                                      new XElement("FirstName", "Joe"),
                                      new XElement("LastName", "Rattz"));
        Console.WriteLine(name1);

        //-- Casting an Element to Its Value’s Data Type Outputs the Value
        Console.WriteLine(name);
        Console.WriteLine((string)name);

        //--Different Node Value Types Retrieved via Casting to the Node Value’s Type
        XElement count = new XElement("Count", 12);
        Console.WriteLine(count);
        Console.WriteLine((int)count);

        XElement smoker = new XElement("Smoker", false);
        Console.WriteLine(smoker);
        Console.WriteLine((bool)smoker);

        XElement pi = new XElement("Pi", 3.1415926535);
        Console.WriteLine(pi);
        Console.WriteLine((double)pi);


        DeferredQryProblem();


        GenerateXMlFromLinqQry();



    }

    private static void DeferredQryProblem()
    {
        XDocument xDocument = new XDocument(
                    new XElement("BookParticipants",
                    new XElement("BookParticipant",
                    new XAttribute("type", "Author"),
                    new XElement("FirstName", "Joe"),
                    new XElement("LastName", "Rattz")),
                    new XElement("BookParticipant",
                    new XAttribute("type", "Editor"),
                    new XElement("FirstName", "Ewan"),
                    new XElement("LastName", "Buckingham"))));
        IEnumerable<XElement> elements =
        xDocument.Element("BookParticipants").Elements("BookParticipant");
        foreach (XElement element in elements)
        {
            Console.WriteLine("Source element: {0} : value = {1}",
            element.Name, element.Value);
        }
        foreach (XElement element in elements)
        {
            Console.WriteLine("Removing {0} = {1} ...", element.Name, element.Value);
            element.Remove();
        }
        Console.WriteLine(xDocument);


        foreach (XElement element in elements)
        {
            Console.WriteLine("Source element: {0} : value = {1}",
            element.Name, element.Value);
        }
        foreach (XElement element in elements.ToArray())
        {
            Console.WriteLine("Removing {0} = {1} ...", element.Name, element.Value);
            element.Remove();
        }
        Console.WriteLine(xDocument);
    }

    //-- Creating an Attribute and Adding It to Its Element
    private static void CreatingAttribute()
    {
        XElement xBookParticipant = new XElement("BookParticipant", new XAttribute("type", "Author"));
        Console.WriteLine(xBookParticipant);
    }

    //--Creating a Comment with Functional Construction
    private static void CreatingComment()
    {
        XElement xBookParticipant = new XElement("BookParticipant",
                                                  new XComment("This person is retired."));
        Console.WriteLine(xBookParticipant);
    }

    //--Creating a Declaration with Functional Construction
    private static void CreateXmlDeclaration()
    {
        XDocument xDocument = new XDocument(new XDeclaration("1.0", "UTF-8", "yes"),
new XElement("BookParticipant"));
        Console.WriteLine(xDocument);
    }

    private static void GenerateXMlFromLinqQry()
    {
        BookParticipant[] bookParticipants = new[] {new BookParticipant {FirstName = "Joe", LastName = "Rattz",
                                                    ParticipantType = ParticipantTypes.Author},
                                                    new BookParticipant {FirstName = "Ewan", LastName = "Buckingham",
                                                    ParticipantType = ParticipantTypes.Editor}
                                                    };
        XElement xBookParticipants =
        new XElement("BookParticipants",
                     bookParticipants.Select(p =>
                new XElement("BookParticipant",
                new XAttribute("type", p.ParticipantType),
                new XElement("FirstName", p.FirstName),
                new XElement("LastName", p.LastName))));


        Console.WriteLine(xBookParticipants);
    }

    //-- Obtaining Elements Without Reaching
    private static void WithoutReaching()
    {
        XDocument xDocument = new XDocument(new XElement("BookParticipants",
                                            new XElement("BookParticipant",
                                            new XAttribute("type", "Author"),
                                            new XElement("FirstName", "Joe"),
                                            new XElement("LastName", "Rattz")),
                                            new XElement("BookParticipant",
                                            new XAttribute("type", "Editor"),
                                            new XElement("FirstName", "Ewan"),
                                            new XElement("LastName", "Buckingham"))));
        IEnumerable<XElement> elements = xDocument.Descendants("BookParticipant");
        foreach (XElement element in elements)
        {
            Console.WriteLine("Element: {0} : value = {1}",
            element.Name, element.Value);
        }


        IEnumerable<XElement> elements1 = xDocument.Descendants("BookParticipant")
                                                   .Where(e => ((string)e.Element("FirstName")) == "Ewan");
        foreach (XElement element1 in elements1)
        {
            Console.WriteLine("Element: {0} : value = {1}",
            element1.Name, element1.Value);
        }

    }

【讨论】：

【解决方案6】：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Xml.Linq;

namespace LinqToXmlTest
{
public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void ReadXml()
    {
        XDocument xdocument = XDocument.Load(Server.MapPath("People.xml"));
        var persons = from person in xdocument.Descendants("Person")
                      select new
                      {
                          Name = person.Element("Name").Value,
                          City = person.Element("City").Value,
                          Age = person.Element("Age").Value
                      };
        litResults.Text = "";
        foreach (var person in persons)
        {
            litResults.Text = litResults.Text + "Name: " + person.Name + "<br/>";
            litResults.Text = litResults.Text + "City: " + person.City + "<br/>";
            litResults.Text = litResults.Text + "Age: " + person.Age + "<br/><br/>";
        }
        if (litResults.Text == "")
            litResults.Text = "No Results...";
    }

    protected void butAdd_Click(object sender, EventArgs e)
    {
        try
        {
            if (txtName.Text == "" || txtCity.Text == "" || txtAge.Text == "")
            {
                lblStatus.ForeColor = System.Drawing.Color.Red;
                lblStatus.Text = "Please Complete the form";
            }
            else
            {
                XDocument xdocumnet = XDocument.Load(Server.MapPath("People.xml"));
                xdocumnet.Element("Persons").Add(new XElement("Person",
                    new XElement("Name", txtName.Text),
                    new XElement("City", txtCity.Text),
                    new XElement("Age", txtAge.Text)));
                xdocumnet.Save(Server.MapPath("People.xml"));
                lblStatus.ForeColor = System.Drawing.Color.Green;
                lblStatus.Text = "Data Successfully loaded to xml file";
                txtName.Text = "";
                txtCity.Text = "";
                txtAge.Text = "";
                ReadXml();
            }
        }
        catch
        {
            lblStatus.ForeColor = System.Drawing.Color.Red;
            lblStatus.Text = "Sorry unable to precess request.Please try again";
        }


    }

    protected void butRead_Click(object sender, EventArgs e)
    {
        ReadXml();
        lblStatus.Text = "";
    }

    protected void btnUpdate_Click(object sender, EventArgs e)
    {
        try
        {
            if (txtName.Text == "" || txtCity.Text == "" || txtAge.Text == "")
            {
                lblStatus.ForeColor = System.Drawing.Color.Red;
                lblStatus.Text = "Please enter all details in the form";
            }
            else
            {
                XDocument xdocument = XDocument.Load(Server.MapPath("People.xml"));
                var persondata = (from person in xdocument.Descendants("Person")
                                  where person.Element("Name").Value.Equals(txtName.Text)
                                  select person).Single();


                persondata.Element("City").Value = txtCity.Text;
                persondata.Element("Age").Value = txtAge.Text;

                xdocument.Save(Server.MapPath("People.xml"));
                lblStatus.ForeColor = System.Drawing.Color.Green;
                lblStatus.Text = "The data updated successfully";
                ReadXml();
            }
        }
        catch(Exception ex)
        {
            lblStatus.ForeColor = System.Drawing.Color.Red;
            lblStatus.Text = ex.Message;
        }
    }

    protected void btnDelete_Click(object sender, EventArgs e)
    {
        try
        {
            if (txtName.Text == "")
            {
                lblStatus.ForeColor = System.Drawing.Color.Red;
                lblStatus.Text = "Please enter the name of the person to delete...";                    
            }
            else
            {
                XDocument xdocument = XDocument.Load(Server.MapPath("People.xml"));
                var persondata = (from person in xdocument.Descendants("Person")
                                  where person.Element("Name").Value.Equals(txtName.Text)
                                  select person).Single();


                persondata.Remove();
                xdocument.Save(Server.MapPath("People.xml"));
                lblStatus.ForeColor = System.Drawing.Color.Green;
                lblStatus.Text = "The data deleted successfully...";
                txtName.Text = "";
                txtCity.Text = "";
                txtAge.Text = "";
                ReadXml();
            }
        }
        catch (Exception ex)
        {
            lblStatus.ForeColor = System.Drawing.Color.Red;
            lblStatus.Text = ex.Message;
        }
    }
}
}

【讨论】：

仅仅插入一段代码并不能真正帮助人们，尤其是很多代码与实际问题无关