说说NET3.5中的扩展方法

扩展方法配合Lambda表示达,可以方便我们进行数据的查询,看个代码吧:

      IEnumerable<string> x=new List<string> {"1","zzl","good"}; //为对象赋值

       foreach (var info in  x.ForUser("zzl"))   //从其中筛选zzl这个字符

        {

            Response.Write(info);

        }

public static class filter

{

    public static IEnumerable<string> ForUser(this IEnumerable<string> qry, string userName)  

    {

        return from a in qry

               where

                   a.Contains(userName.ToLower())

               select a;

    }

}