C#中对linq where查询的应用

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace LINQ_WHERE
{
    /**//// <summary>
    /// LINQ where子句
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            //1常见的where语句
            List<GustInfo> gList = new List<GustInfo>() 
            {
                new GustInfo(){ Name="DebugLZQ", Age=26,Tel="88888888"},
                new GustInfo(){ Name="cnblogs",Age=6,Tel="666666"},
                new GustInfo(){ Name="M&MSoft",Age=9,Tel="55555"}
            };

            var query = from gust in gList
                        where (gust.Name.Length > 7 || gust.Name.Substring(0, 1) == "M") && gust.Age > 9
                        select new { gust.Name, gust.Age };
            foreach (var g in query)
            {
                Console.WriteLine("{0},{1}", g.Name, g.Age);
            }

            Console.ReadKey(false);

            //2.在where子句中使用自定义函数
            var query2 = from GustInfo gust in gList
                         where gust.Name.Length > 5
                         && Check(gust.Name)
                         select gust;
            foreach (var g in query2)
            {
                Console.WriteLine("{0},{1},{2}", g.Name, g.Age, g.Tel);
            }
            Console.ReadKey(false);

            //3.动态谓词的筛选
            //定义动态谓词数组,在实际开发中可以动态获得
            string[] names = { "SB","XXX","***","@@@","一些敏感词"};

            var query3 = from GustInfo guest in gList
                         where !names.Contains(guest.Name)
                         select guest;

            foreach (var q in query3)
            {
                Console.WriteLine("{0} 年龄：{1},电话：{2}",q.Name,q.Age,q.Tel );
            }
            Console.ReadKey(false);
        }

        //自定义函数
        static bool Check(string name)
        {
            if (name.Substring(0, 1) == "N")
                return false;
            return true;
        }
    }
}

 

 

文章转载自：        Linq中where查询       http://www.studyofnet.com/news/269.html