C# 在Linq到XML中查找元素

我生成了一个XML文件，它看起来像这样：

<?xml version="1.0" encoding="utf-8"?>
<Members xmlns="urn:lst-emp:emp">
  <Member xmlns="">
    <!--Info for Member TESTER-->
    <AccountName>Test Name</AccountName>
    <AccountNumber>Test Number</AccountNumber>
    <AccountBalance>Test Balance</AccountBalance>
  </Member>
  <Member xmlns="">
    <!--Info for Member Jeff Reed-->
    <AccountName>Jeff Reed</AccountName>
    <AccountNumber>5929</AccountNumber>
    <AccountBalance>9223.01</AccountBalance>
  </Member>
</Members>

    internal static XElement FindMember(String validationName)
    {
        XDocument doc = XDocument.Load(Application.LocalUserAppDataPath + "\\members.xml");

        XElement accountNameElement = doc.Root
                                         .Elements("Member")
                                         .Elements("AccountName")
                                         .FirstOrDefault(e => e.Value == validationName);

        if (accountNameElement != default(XElement))
            return accountNameElement.Parent;
        return default(XElement);
    }

        XElement memberElement= FindMember("Test Name");
        if (memberElement== default(XElement))
            Console.WriteLine("Not Found");
        else
        {
            Console.WriteLine("Found {0}, {1}, {2}"
                , memberElement.Element("AccountName").Value
                , memberElement.Element("AccountNumber").Value
                , memberElement.Element("AccountBalance").Value);
        }

---

以下代码为您提供匹配元素的帐号

members.Where(x=> x.Element("AccountName").Value==validationName).Select(x=> x.Element("AccountNumber").Value).FirstOrDefault();

---

父母是关键。大概是这样的：

<?xml version="1.0" encoding="utf-8"?>
<Members xmlns="urn:lst-emp:emp">
  <Member xmlns="">
    <!--Info for Member TESTER-->
    <AccountName>Test Name</AccountName>
    <AccountNumber>Test Number</AccountNumber>
    <AccountBalance>Test Balance</AccountBalance>
  </Member>
  <Member xmlns="">
    <!--Info for Member Jeff Reed-->
    <AccountName>Jeff Reed</AccountName>
    <AccountNumber>5929</AccountNumber>
    <AccountBalance>9223.01</AccountBalance>
  </Member>
</Members>

    internal static XElement FindMember(String validationName)
    {
        XDocument doc = XDocument.Load(Application.LocalUserAppDataPath + "\\members.xml");

        XElement accountNameElement = doc.Root
                                         .Elements("Member")
                                         .Elements("AccountName")
                                         .FirstOrDefault(e => e.Value == validationName);

        if (accountNameElement != default(XElement))
            return accountNameElement.Parent;
        return default(XElement);
    }

        XElement memberElement= FindMember("Test Name");
        if (memberElement== default(XElement))
            Console.WriteLine("Not Found");
        else
        {
            Console.WriteLine("Found {0}, {1}, {2}"
                , memberElement.Element("AccountName").Value
                , memberElement.Element("AccountNumber").Value
                , memberElement.Element("AccountBalance").Value);
        }

这样调用：

<?xml version="1.0" encoding="utf-8"?>
<Members xmlns="urn:lst-emp:emp">
  <Member xmlns="">
    <!--Info for Member TESTER-->
    <AccountName>Test Name</AccountName>
    <AccountNumber>Test Number</AccountNumber>
    <AccountBalance>Test Balance</AccountBalance>
  </Member>
  <Member xmlns="">
    <!--Info for Member Jeff Reed-->
    <AccountName>Jeff Reed</AccountName>
    <AccountNumber>5929</AccountNumber>
    <AccountBalance>9223.01</AccountBalance>
  </Member>
</Members>

    internal static XElement FindMember(String validationName)
    {
        XDocument doc = XDocument.Load(Application.LocalUserAppDataPath + "\\members.xml");

        XElement accountNameElement = doc.Root
                                         .Elements("Member")
                                         .Elements("AccountName")
                                         .FirstOrDefault(e => e.Value == validationName);

        if (accountNameElement != default(XElement))
            return accountNameElement.Parent;
        return default(XElement);
    }

        XElement memberElement= FindMember("Test Name");
        if (memberElement== default(XElement))
            Console.WriteLine("Not Found");
        else
        {
            Console.WriteLine("Found {0}, {1}, {2}"
                , memberElement.Element("AccountName").Value
                , memberElement.Element("AccountNumber").Value
                , memberElement.Element("AccountBalance").Value);
        }

---

您已经知道如何获取

AccountName

，您可以以完全相同的方式获取

AccountNumber

：

member.Element（“AccountNumber”）.Value

。此外，永远不要使用

float

或

double

来表示货币值。但是如何找到特定的元素AccountNumber？我在每个AccountName中搜索匹配项，但一旦找到它匹配的元素，我就需要找到它的AccountNumber。嗯，一旦找到它匹配的元素，你就有了它匹配的元素，这正是你要寻找的。我认为

Single（）

比这里的

FirstOrDefault（）

更有意义。@svick:是的。但是最好使用

SingleOrDefault（）

如何覆盖找到的值？