LINQ Sample

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

namespace cInitialize
{

    class Country
    {
        public string Name { get; set; } public int Area { get; set; } public int Population { get; set; }
    }

    class EtcInfo
    {
        public string Name { get; set; }
        public string Etc { get; set; }
    }

    class cQuery2
    {
        static public void CallMethod()
        {
            List listCon = new List{
                new Country{Name="한국",Area=1000000,Population=5000},
                new Country{Name="일본",Area=500000,Population=3000},
                new Country{Name="중국",Area=2000000,Population=50000},
                new Country{Name="대만",Area=800000,Population=4000},
                new Country{Name="한국",Area=1500000,Population=5500},
                new Country{Name="대만",Area=800000,Population=4000}
                };

            List listEtc = new List
            {
                new EtcInfo{Name="한국",Etc="아시아1"}, 
                new EtcInfo{Name="일본",Etc="아시아2"},
                new EtcInfo{Name="중국",Etc="아시아3"},
                new EtcInfo{Name="대만",Etc="아시아4"}
            };


            /* 1. LINQ where절 */
            IEnumerable coutryAreaQuery = from country in listCon where country.Area > 500000 select country;

            foreach (var item in coutryAreaQuery)
            {
                Console.WriteLine("{0}:면적<{1}>, 인구<{2}>", item.Name, item.Area, item.Population);
            }


            /* 2. LINQ group */
            Console.WriteLine("=====================================");

            var queryContryGroups = from c in listCon group c by c.Name;

            foreach (var item in queryContryGroups)
            {
                Console.WriteLine("----{0} 그룹----", item.Key);
                foreach (var item2 in item)
                {
                    Console.WriteLine("{0}:면적<{1}>, 인구<{2}>", item2.Name, item2.Area, item2.Population);
                }
            }

            Console.WriteLine();


            /* 3. LINQ where절2 */
            IEnumerable queryCountryPop = from c in listCon where c.Population > 30000 && c.Population < 60000 select c;

            foreach (var item in queryCountryPop)
            {
                Console.WriteLine("{0}:면적<{1}>, 인구<{2}>", item.Name, item.Area, item.Population);
            }

            Console.WriteLine();


            /* 5. LINQ orderby절 */
            IEnumerable querySortedCountries = from c in listCon orderby c.Area ascending, c.Name descending select c;

            foreach (var item in querySortedCountries)
            {
                Console.WriteLine("{0}:면적<{1}>, 인구<{2}>", item.Name, item.Area, item.Population);
            }

            Console.WriteLine();


            /* 6. LINQ join절 */
            var categoryQuery = from c in listCon join e in listEtc on c.Name equals e.Name select new { Name = c.Name, Area = c.Area, Population = c.Population, Etc = e.Etc };

            foreach (var item in categoryQuery)
            {
                Console.WriteLine("{0}:면적<{1}>, 인구<{2}>, 분류<{3}>", item.Name, item.Area, item.Population, item.Etc);
            }

            Console.WriteLine();


            /* 7. LINQ let절*/
            string[] PhoneNum = { "010-333-5555", "010-243-5434", "011-3243-2533" };

            IEnumerable queryFirstNum = from p in PhoneNum let firstNum = p.Split(new char[] { '-' })[0] select firstNum;

            foreach (var item in queryFirstNum)
            {
                Console.WriteLine(item);
            }

            Console.WriteLine();

            string[] PhoneNum2 = { "010-333-5555", "010-243-5434", "011-3243-2533" };

            var queryFirstNum2 = from p in PhoneNum2 select new { Num1 = p.Split('-')[0], Num2 = p.Split('-')[1], Num3 = p.Split('-')[2] };

            foreach (var item in queryFirstNum2)
            {
                Console.WriteLine("{0}){1}_{2}", item.Num1, item.Num2, item.Num3);
            }

            Console.WriteLine();
        }
    }
}