IEnumerable<string> x=new List<string> {"1","zzl","good"}; //為對象賦值

       foreach (var info in  x.ForUser("zzl"))   //從其(qi)中篩選(xuan)zzl這個(ge)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;

    }

}