转换

LinqStudy.Test/LinqToObject/ConvertTest.cs

@@ -1,22 +0,0 @@
-using System;
-using System.Collections;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-
-using Xunit;
-
-namespace LinqStudy.Test.LinqToObject
-{
-    /// <summary>
-    /// 转换运算符
-    /// </summary>
-    public class ConvertTest 
-    {
-        [Fact]
-        public void Test()
-        {
-           var cc=  Enumerable.Empty<string>();
-        }
-    }
-}

LinqStudy.Test/LinqToObject/TypeConvertTest.cs

@@ -0,0 +1,80 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Text;
+using System.Data;
+using System.Data.SqlTypes;
+using System.Data.Common;
+
+using Xunit;
+
+namespace LinqStudy.Test.LinqToObject
+{
+    /// <summary>
+    /// 转换运算符
+    /// </summary>
+    public class TypeConvertTest 
+    {
+        /// <summary>
+        ///  AsEnumeralbe：
+        /// System.Linq.Enumeralbe中，扩展方法
+        /// AsEnumeralbe() 是延迟执行
+        /// </summary>
+        [Fact]
+        public void AsEnumeralbe_Test()
+        {
+            DataTable dt=new DataTable();
+            DataColumn col_id=new DataColumn("Id");
+            col_id.AllowDBNull=false;
+            col_id.AutoIncrementSeed=1;
+            col_id.AutoIncrement=true;
+            col_id.AutoIncrementStep=1;
+            col_id.DataType=typeof(int);
+
+            DataColumn col_name=new DataColumn("Name");
+            col_name.AllowDBNull=true;
+            col_name.AutoIncrement=false;
+            col_name.DataType=typeof(string);
+            col_name.DefaultValue=string.Empty;
+
+            DataColumn col_age=new DataColumn("Age");
+            col_age.AllowDBNull=false;
+            col_age.AutoIncrement=false;
+            col_age.DataType=typeof(int);
+            col_age.DefaultValue=20;
+
+            dt.Columns.Add(col_id);
+            dt.Columns.Add(col_name);
+            dt.Columns.Add(col_age);
+
+            var row_one = dt.NewRow();
+            row_one[1]="王高峰";
+            row_one[2]=21;
+
+            dt.Rows.Add(row_one);
+
+            var cc = from row in dt.Select()
+                     select row;
+            var dd = cc.ToList();
+
+        }
+
+        /// <summary>
+        /// 1.IEnumeralbe 转换为 IQueryable
+        /// 2.IEnumeralbe<T> 转换为 IQueryable<T>
+        /// </summary>
+        [Fact]
+        public void AsQueryable_Test()
+        {
+           IEnumerable bb= Enumerable.Range(1,100);
+
+           var cc=bb.AsQueryable();
+
+           int[] t=new int[]{1,2,3};
+
+           t.AsEnumerable();
+        }
+    }
+}