linq

AdvancedC#Grammer/MySolution/MyConsoleApp/Work/AsyncAwaitWork.cs

@@ -0,0 +1,47 @@
+namespace MyConsoleApp.Work
+{
+    public class AsyncAwaitWork
+    {
+        private static Task Test()
+        {
+            System.Console.WriteLine("Start Test");
+            Task t = Task.Delay(3000);
+            return t;
+        }
+
+        private static async void TestAsync()
+        {
+            System.Console.WriteLine("Start Test");
+            Task t = Task.Delay(3000);
+            await t; // 함수 내부에서는 동기, 함수 호출부에서는 비동기로 처리됨
+            System.Console.WriteLine("End TestAsync");
+        }
+
+        private static async Task<int> TestAsync2()
+        {
+            System.Console.WriteLine("Start Test");
+            Task t = Task.Delay(3000);
+            await t; 
+            System.Console.WriteLine("End TestAsync");
+
+            return 1;
+        }
+
+        public async static void DoTest()
+        {
+            // Task t = Test();
+            // t.Wait();
+
+            //TestAsync();
+            await TestAsync2(); // 메인 함수도 동기로 처리됨
+
+            int res = await TestAsync2();
+
+            System.Console.WriteLine("While start");
+            while (true)
+            {
+
+            }
+        }
+    }
+}

AdvancedC#Grammer/MySolution/MyConsoleApp/Work/LinqWork.cs

@@ -0,0 +1,160 @@
+using System.Diagnostics;
+using System.Security.Cryptography;
+
+namespace MyConsoleApp.Work
+{
+    public class LinqWork
+    {
+        private static List<Player> _players = new List<Player>();
+
+        private static void InitInstance()
+        {
+            Random rand = new Random();
+            for (int i = 0; i < 100; i++)
+            {
+                ClassType type = ClassType.Knight;
+                switch (rand.Next(0, 3))
+                {
+                    case 1:
+                        type = ClassType.Archer;
+                        break;
+                    case 2:
+                        type = ClassType.Mage;
+                        break;
+                }
+
+                Player player = new Player()
+                {
+                    ClassType = type,
+                    Level = rand.Next(1, 100),
+                    Hp = rand.Next(100, 1000),
+                    Attack = rand.Next(5, 50)
+                };
+
+                for (int j = 0; j < 5; j++)
+                {
+                    player.Items.Add(rand.Next(1, 100));
+                }
+
+                _players.Add(player);
+            }
+        }
+
+        public static void DoTest()
+        {
+            InitInstance();
+
+            // Q1) 레벨 50 이상인 Knight를 레벨 오름차순으로 정렬
+
+            Stopwatch sw = new Stopwatch();
+            sw.Start();
+            // Without Linq
+            {
+                List<Player> players = GetHighLevelKnight();
+                foreach (Player player in players)
+                {
+                    System.Console.WriteLine($"[{player.Level}] {player.Hp}");
+                }
+            }
+            System.Console.WriteLine($"{sw.ElapsedMilliseconds}ms");
+
+            System.Console.WriteLine("---------------------");
+
+            sw.Restart();
+            // With Linq
+            {
+                var players = 
+                    from p in _players
+                    where p.ClassType == ClassType.Knight && p.Level >= 50
+                    orderby p.Level
+                    select p;
+
+                foreach (Player player in players)
+                {
+                    System.Console.WriteLine($"[{player.Level}] {player.Hp}");
+                }
+            }
+            System.Console.WriteLine($"{sw.ElapsedMilliseconds}ms");
+
+            // from 중첩
+            // Q2) id가 30 미만인 모든 아이템 목록 추출
+            {
+                var playerItems =
+                    from p in _players
+                    from i in p.Items
+                    where i < 30
+                    select new { p, i };
+                
+                var li = playerItems.ToList();
+                System.Console.WriteLine($"Count: {li.Count}");
+            }
+
+            // grouping
+            {
+                var playerByLevel =
+                    from p in _players
+                    group p by p.Level into g
+                    orderby g.Key
+                    select new { g.Key, Players = g };
+            }
+
+            // join
+            {
+                List<int> levels = new List<int>() { 1, 5, 10 };
+                var players = 
+                    from p in _players
+                    join l in levels
+                    on p.Level equals l
+                    select p;
+            }
+
+            // Linq 표준 연산자
+            {
+                var players = 
+                    from p in _players
+                    where p.ClassType == ClassType.Knight && p.Level >= 50
+                    orderby p.Level
+                    select p;
+
+                var players2 = _players
+                    .Where(p => p.ClassType == ClassType.Knight && p.Level >= 50)
+                    .OrderBy(p => p.Level)
+                    .Select(p => p);
+            }
+        }
+
+        private static List<Player> GetHighLevelKnight()
+        {
+            List<Player> players = new List<Player>();
+            foreach (Player player in _players)
+            {
+                if (player.ClassType != ClassType.Knight)
+                    continue;
+                if (player.Level < 50)
+                    continue;
+
+                players.Add(player);
+            }
+
+            players.Sort((lhs, rhs) => { return lhs.Level - rhs.Level; });
+
+            return players;
+        }
+    }
+
+    public enum ClassType
+    {
+        Knight,
+        Archer,
+        Mage,
+    }
+
+    public class Player
+    {
+        public ClassType ClassType { get; set; }
+        public int Level { get; set; }
+        public int Hp { get; set; }
+        public int Attack { get; set; }
+        public List<int> Items { get; set; } = new List<int>();
+    }
+}