Dictionary<string, string> myDic = new Dictionary<string, string>();myDic.Add("aaa", "111");myDic.Add("bbb", "222");myDic.Add("ccc", "333");myDic.Add("ddd", "444");//如果添加已经存在的键，add方法会抛出异常try{myDic.Add("ddd","ddd");}catch (ArgumentException ex){Console.WriteLine("此键已经存在：" + ex.Message);}//解决add()异常的方法是用ContainsKey()方法来判断键是否存在if (!myDic.ContainsKey("ddd")){myDic.Add("ddd", "ddd");}else{Console.WriteLine("此键已经存在：");}//而使用索引器来负值时，如果建已经存在，就会修改已有的键的键值，而不会抛出异常
myDic ["ddd"]="ddd";myDic["eee"] = "555";//使用索引器来取值时，如果键不存在就会引发异常try{Console.WriteLine("不存在的键""fff""的键值为：" + myDic["fff"]);}catch (KeyNotFoundException ex){Console.WriteLine("没有找到键引发异常：" + ex.Message);}//解决上面的异常的方法是使用ContarnsKey() 来判断时候存在键，如果经常要取健值得化最好用 TryGetValue方法来获取集合中的对应键值string value = "";if (myDic.TryGetValue("fff", out value)){Console.WriteLine("不存在的键""fff""的键值为：" + value );}else{    Console.WriteLine("没有找到对应键的键值");}//下面用foreach 来遍历键值对//泛型结构体 用来存储健值对foreach (KeyValuePair<string, string> kvp in myDic){Console.WriteLine("key={0},value={1}", kvp.Key, kvp.Value);}//获取值得集合foreach (string s in myDic.Values){Console.WriteLine("value={0}", s);}//获取值得另一种方式
Dictionary<string, string>.ValueCollection values = myDic.Values;foreach (string s in values){Console.WriteLine("value={0}", s);}

<?xml version="1.0" encoding="UTF-8"?>
<data><resource key="123">foo</resource><resource key="456">bar</resource><resource key="789">bar</resource></data>
i want to put this into a Dictionary (sorted) as key value pairs. i.e: 123:foo, 456:bar...etcthe keys are unknown.string s = "<data><resource key=/"123/">foo</resource><resource key=/"456/">bar</resource><resource key=/"789/">bar</resource></data>";XmlDocument xml = new XmlDocument();xml.LoadXml(s);XmlNodeList resources = xml.SelectNodes("data/resource");SortedDictionary<string,string> dictionary = new SortedDictionary<string,string>();foreach (XmlNode node in resources){dictionary.Add(node.Attributes["key"].Value, node.InnerText);}linq to xml:var xml = XDocument.Load(...);
var sequence = from e in xml.Root.Elements() let key = (string)e.Attribute("key")order by keyselect new { Key = key, Value = (string)e };