c# [app.config] 找不到 "ConfigurationManager",即使添加了命名空间 using System.Configuration;

时间:2016年08月15日17:06:10 星期一  Ken
http://stackoverflow.com/questions/1274852/the-name-configurationmanager-does-not-exist-in-the-current-context
解决方法:需要添加引用  system.configuration

The
name 'ConfigurationManager' does not exist in the current context

It's not only necessary to use the namespace 

System.Configuration

.
You have also to add the reference to the assembly 

System.Configuration.dll

==============================================================

写

<appSettings>

    <add key="Host" value="smtp.163.com" />

    <add key="Port" value="25" />

  </appSettings>

读

private string strHost = ConfigurationManager.AppSettings["Host"];

参考: http://www.cnblogs.com/go-onxp/archive/2012/11/07/2758144.html
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另外一个异常  "app.config配置系统未能初始化"

解决方法: appSettings元素调到configSections元素后面就行了。