风影ASP.NET基础教学 13 NET3.0特性补充

staticclassHelper{

{

//类型推导功能

return(T)obj;

}

}

publicstaticclassHelper2

{

publicstaticstringShowTime(thisStringobj)

{

returnobj+DateTime.Now.ToString();

}

}

classProgram

{

staticvoidMain(string[]args)

{

#region匿名类型的局部变量

//varstr="Hello";

//varnum=22.3;

//vararr=new[]{"1","2","3"};

//foreach(variteminarr)

//{

//Console.WriteLine(item);

//}

#endregion

#region匿名类型

//varTest=new{name="zhangsan",id=12};

//Console.WriteLine(Test.name);

#endregion

#region扩展方法

//varabc="hello".ShowTime();

//Console.WriteLine(abc);

#endregion

#region对象初始化器

#endregion

#region集合初始化器

List<String>list=newList<string>(){"1","3","ggf"};

foreach(variteminlist)

{

Console.WriteLine(item);

}

#endregion

#regionLambda表达式

//所谓Lambda表达式实际上是对一个集合进行数据筛选和计算用的

List<object>user=newList<object>{

new{Id=1,Name="YJingLee",Age=22},

new{Id=2,Name="XieQing",Age=25},

};

//获取特定人时所用的过滤条件，p参数属于User类型

varresults=user.Where(p=>p.Cast(new{Id=0,Name=string.Empty,Age=0}).Name=="XieQing").ToList();

foreach(variteminresults)

{

Console.WriteLine(item.Cast(new{Id=0,Name="",Age=0}).Name);

}

//用User对象的Age值计算平均年龄

varaverage=user.Average(p=>p.Cast(new{Id=0,Name=string.Empty,Age=0}).Age);

#endregion

}

}