添加反序

LinqStudy.Test/LinqToObject/OrderTest.cs

@@ -24,18 +24,15 @@ namespace LinqStudy.Test.LinqToObject
         {
             List<Person> peoples = new List<Person>()
             {
-                new Person(){ Id = 1, Name = "张三", Age=33 },
+                new Person(){ Id = 3, Name = "张三", Age=33 },
-                new Person(){ Id = 3, Name = "李四", Age=65 },
+                new Person(){ Id = 5, Name = "王五", Age=55 },
-                new Person(){ Id = 2, Name = "王五", Age=17 },
+                new Person(){ Id = 4, Name = "李四", Age=44 },
             };
 
             var oprationItem = peoples.OrderBy(p => p.Id);
+            var firtName = oprationItem.First().Name;
 
-            var firtId = oprationItem.First().Id;
+            Assert.Equal("张三", firtName);
-            var lastId = oprationItem.Last().Id;
-
-            Assert.Equal(1,firtId);
-            Assert.Equal(3, lastId);
         }
 
         /// <summary>
@@ -46,21 +43,22 @@ namespace LinqStudy.Test.LinqToObject
         {
             List<Person> peoples = new List<Person>()
             {
-                new Person(){ Id = 1, Name = "张三", Age=33 },
+                new Person(){ Id = 3, Name = "张三", Age=33 },
-                new Person(){ Id = 3, Name = "李四", Age=65 },
+                new Person(){ Id = 5, Name = "王五", Age=55 },
-                new Person(){ Id = 2, Name = "王五", Age=17 },
+                new Person(){ Id = 4, Name = "李四", Age=44 },
             };
 
             var oprationItem = peoples.OrderBy(p => p.Id);
 
-            var addItem = new Person() { Id = 4, Name = "赵立", Age = 87 };
+            peoples.Insert(0, new Person() { Id = 6, Name = "赵六", Age = 66 });
-            peoples.Add(addItem);
 
-            var firtId = oprationItem.First().Id;
+            //执行一次排序
-            var lastId = oprationItem.Last().Id;
+            var firtName = oprationItem.First().Name;
+            //再执行一次排序
+            var lastName = oprationItem.Last().Name;
 
-            Assert.Equal(1, firtId);
+            Assert.Equal("张三", firtName);
-            Assert.Equal(4, lastId);
+            Assert.Equal("王五", lastName);
         }
 
         /// <summary>
@@ -124,7 +122,7 @@ namespace LinqStudy.Test.LinqToObject
 
             var oprationItem = peoples.OrderByDescending(p => p.Id);
 
-            var addItem = new Person() { Id = 4, Name = "赵立", Age = 87 };
+            var addItem = new Person() { Id = 4, Name = "赵六", Age = 87 };
             peoples.Add(addItem);
 
             var firtId = oprationItem.First().Id;
@@ -169,12 +167,12 @@ namespace LinqStudy.Test.LinqToObject
                 new Person(){ Id = 1, Name = "张三", Age=44 },
                 new Person(){ Id = 1, Name = "李四", Age=33 },
                 new Person(){ Id = 2, Name = "王五", Age=22 },
-                new Person(){ Id = 2, Name = "赵立", Age=11 },
+                new Person(){ Id = 2, Name = "赵六", Age=11 },
             };
 
             //先按Id排序，Id相同的，再按年龄排序。
             var oprationItem = peoples.OrderBy(p => p.Id).ThenBy(p => p.Age).Select(p => p.Name);
-            var expected = new List<string>() { "李四", "张三", "赵立", "王五" };
+            var expected = new List<string>() { "李四", "张三", "赵六", "王五" };
 
             Assert.Equal(expected, oprationItem);
         }
@@ -190,7 +188,7 @@ namespace LinqStudy.Test.LinqToObject
                 new Person(){ Id = 1, Name = "张三", Age=44 },
                 new Person(){ Id = 1, Name = "李四", Age=33 },
                 new Person(){ Id = 2, Name = "王五", Age=22 },
-                new Person(){ Id = 2, Name = "赵立", Age=11 },
+                new Person(){ Id = 2, Name = "赵六", Age=11 },
             };
 
             var oprationItem = peoples.OrderBy(p => p.Id).ThenBy(p => p.Age);
@@ -199,7 +197,7 @@ namespace LinqStudy.Test.LinqToObject
             peoples.Add(addItme);
 
             var actual = oprationItem.Select(p => p.Name).ToList();
-            var expected = new List<string>() { "刘能", "李四", "张三", "赵立", "王五" };
+            var expected = new List<string>() { "刘能", "李四", "张三", "赵六", "王五" };
 
             Assert.Equal(expected, actual);
         }
@@ -215,13 +213,13 @@ namespace LinqStudy.Test.LinqToObject
                 new Person(){ Id = 1, Name = "张三", Age=44 },
                 new Person(){ Id = 1, Name = "李四", Age=33 },
                 new Person(){ Id = 2, Name = "王五", Age=22 },
-                new Person(){ Id = 2, Name = "赵立", Age=11 },
+                new Person(){ Id = 2, Name = "赵六", Age=11 },
             };
 
-            var oprationItem = peoples.OrderBy(p => p, new PersonComparer()).ThenBy(p=>p.Age,Comparer<int>.Default);
+            var oprationItem = peoples.OrderBy(p => p, new PersonComparer()).ThenBy(p => p.Age, Comparer<int>.Default);
 
             var actual = oprationItem.Select(p => p.Name).ToList();
-            var expected = new List<string>() {"李四", "张三", "赵立", "王五" };
+            var expected = new List<string>() { "李四", "张三", "赵六", "王五" };
 
             Assert.Equal(expected, actual);
         }
@@ -239,12 +237,12 @@ namespace LinqStudy.Test.LinqToObject
                 new Person(){ Id = 1, Name = "张三", Age=44 },
                 new Person(){ Id = 1, Name = "李四", Age=33 },
                 new Person(){ Id = 2, Name = "王五", Age=22 },
-                new Person(){ Id = 2, Name = "赵立", Age=11 },
+                new Person(){ Id = 2, Name = "赵六", Age=11 },
             };
 
             //先按Id排序，Id相同的，再按年龄排序。
             var oprationItem = peoples.OrderBy(p => p.Id).ThenByDescending(p => p.Age).Select(p => p.Name);
-            var expected = new List<string>() {"张三","李四","王五", "赵立"};
+            var expected = new List<string>() { "张三", "李四", "王五", "赵六" };
 
             Assert.Equal(expected, oprationItem);
         }
@@ -260,7 +258,7 @@ namespace LinqStudy.Test.LinqToObject
                 new Person(){ Id = 1, Name = "张三", Age=44 },
                 new Person(){ Id = 1, Name = "李四", Age=33 },
                 new Person(){ Id = 2, Name = "王五", Age=22 },
-                new Person(){ Id = 2, Name = "赵立", Age=11 },
+                new Person(){ Id = 2, Name = "赵六", Age=11 },
             };
 
             var oprationItem = peoples.OrderBy(p => p.Id).ThenByDescending(p => p.Age);
@@ -269,7 +267,7 @@ namespace LinqStudy.Test.LinqToObject
             peoples.Add(addItme);
 
             var actual = oprationItem.Select(p => p.Name).ToList();
-            var expected = new List<string>() { "张三", "李四", "刘能", "王五","赵立" };
+            var expected = new List<string>() { "张三", "李四", "刘能", "王五", "赵六" };
 
             Assert.Equal(expected, actual);
         }
@@ -285,16 +283,85 @@ namespace LinqStudy.Test.LinqToObject
                 new Person(){ Id = 1, Name = "张三", Age=44 },
                 new Person(){ Id = 1, Name = "李四", Age=33 },
                 new Person(){ Id = 2, Name = "王五", Age=22 },
-                new Person(){ Id = 2, Name = "赵立", Age=11 },
+                new Person(){ Id = 2, Name = "赵六", Age=11 },
             };
 
             var oprationItem = peoples.OrderBy(p => p, new PersonComparer()).ThenByDescending(p => p.Age, Comparer<int>.Default);
 
             var actual = oprationItem.Select(p => p.Name).ToList();
-            var expected = new List<string>() { "张三","李四",  "王五", "赵立",};
+            var expected = new List<string>() { "张三", "李四", "王五", "赵六", };
 
             Assert.Equal(expected, actual);
         }
         #endregion
+
+        #region Resevse
+        /// <summary>
+        /// Resevse：反序序列(逆向)；立即执行
+        /// </summary>
+        [Fact]
+        public void Resevse_Test()
+        {
+            List<Person> peoples = new List<Person>()
+            {
+                new Person(){ Id = 1, Name = "张三", Age=44 },
+                new Person(){ Id = 2, Name = "李四", Age=33 },
+            };
+
+            //简单逆序
+            peoples.Reverse();
+            var firstId = peoples.First().Id;
+
+            Assert.Equal(2, firstId);
+        }
+
+        /// <summary>
+        /// Resevse：反序序列(逆向)；立即执行
+        /// </summary>
+        [Fact]
+        public void Resevse_immediately_Test()
+        {
+            List<Person> peoples = new List<Person>()
+            {
+                new Person(){ Id = 1, Name = "张三", Age=33 },
+                new Person(){ Id = 2, Name = "李四", Age=44 },
+            };
+
+            //简单逆序
+            peoples.Reverse();
+
+            peoples.Add(new Person() { Id = 3, Name = "云花公主", Age = 18 });
+
+            //数据源变化，不影响结果。
+            var firstId = peoples.First().Id;
+
+            Assert.Equal(2, firstId);
+        }
+
+        /// <summary>
+        /// Resevse重载：index开始项，count反序项的数量
+        /// </summary>
+        [Fact]
+        public void Resevse_index_count_Test()
+        {
+            List<Person> peoples = new List<Person>()
+            {
+                new Person(){ Id = 1, Name = "张三", Age=44 },
+                new Person(){ Id = 2, Name = "李四", Age=33 },
+                new Person(){ Id = 3, Name = "王五", Age=44 },
+                new Person(){ Id = 4, Name = "赵六", Age=33 },
+            };
+
+            //从指定位置开始逆序指定数量的项。
+            //从序号为1(第2项)开始，反序2项：即反序第2第3两项。
+            peoples.Reverse(1, 2);
+
+            var secondId = peoples[1].Id;
+            var thirdId = peoples[2].Id;
+
+            Assert.Equal(3, secondId);
+            Assert.Equal(2, thirdId);
+        }
+        #endregion
     }
 }