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<?xml version="1.0" encoding="utf-8" ?> 

<configuration> 

 <connectionStrings> 

  <add name="conn" connectionString="this is connection string"/> 

 </connectionStrings> 

 <appSettings> 

  <add key="key1" value="value1" /> 

  <add key="key2" value="value2" /> 

 </appSettings> 

</configuration>

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using System; 

using System.Collections.Generic; 

using System.Collections; 

using System.Linq; 

using System.Text; 

using System.Configuration; 

namespace AppConfig 

{ 

  class Program 

  { 

    static void Main(string[] args) 

    { 

      Console.WriteLine("ConnectionStrings:"); 

      // ConfigurationManager.ConnectionStrings是一个ConnectionStringSettingsCollection对象 

      // 按数字循环得到一个个ConnectionStringSettings对象 

      // 每个ConnectionStringSettings对象有Name和ConnectionString属性 

      for (int i = 0; i < ConfigurationManager.ConnectionStrings.Count; i++) 

      { 

        string name = ConfigurationManager.ConnectionStrings[i].Name; 

        string connectionString = ConfigurationManager.ConnectionStrings[i].ConnectionString; 

        Console.WriteLine(i.ToString() + ". " + name + " = " + connectionString); 

      } 

      //也可以如下操作，使用ConnectionStringSettings类型来进行foreach遍历 

      foreach (ConnectionStringSettings conn in ConfigurationManager.ConnectionStrings) 

      { 

        string name = conn.Name; 

        string connectionString = conn.ConnectionString; 

        Console.WriteLine(name + " = " + connectionString); 

      } 

      //直接获取conn的值 

      Console.WriteLine("\r\nGet the value of the node named \"conn\":"); 

      Console.WriteLine(ConfigurationManager.ConnectionStrings["conn"].ConnectionString); 

      Console.WriteLine(""); 

      Console.WriteLine("AppSettings:"); 

      //AppSettings是NameValueConnection类型，使用AllKeys返回一个所有Key组成的字符串数组 

      string[] keys = ConfigurationManager.AppSettings.AllKeys; 

      for (int i = 0; i < keys.Length; i++) 

      { 

        string key = keys[i]; 

        //通过Key来索引Value 

        string value = ConfigurationManager.AppSettings[key]; 

        Console.WriteLine(i.ToString() + ". " + key + " = " + value); 

      } 

      // 没有NameValuePair这样的对象，所以无法使用foreach来进行循环 

      //直接获取key1的值 

      Console.WriteLine("\r\nGet the value of the key named \"key1\":"); 

      Console.WriteLine(ConfigurationManager.AppSettings["key1"]); 

      //pause the process 

      Console.ReadKey(); 

    } 

  } 

}