C# dynamic类型使用详解

dynamic obj = 10;  // 可以是整数
obj = "Hello";     // 可以变成字符串
obj = new { Name = "John", Age = 30 }; // 也可以是匿名类型

dynamic obj = new { Name = "John", Age = 30 };
Console.WriteLine(obj.Name); // 输出: John

dynamic math = new { Add = (Func<int, int, int>)((x, y) => x + y) };
Console.WriteLine(math.Add(2, 3)); // 输出: 5

object obj1 = 10;
// obj1.SomeMethod(); // 编译错误：object 没有 SomeMethod 方法

dynamic obj2 = 10;
// obj2.SomeMethod(); // 编译通过，但运行时抛出异常

dynamic dynamicVariable = 123; // 编译器不检查类型
int staticVariable = 123;      // 编译器推断为 int

object obj = "Hello";
// Console.WriteLine(obj.Length); // 编译错误
Console.WriteLine(((string)obj).Length); // 强制转换

dynamic dyn = "Hello";
Console.WriteLine(dyn.Length); // 运行时解析，编译通过

using System.Dynamic;

dynamic expando = new ExpandoObject();
expando.Name = "John";
expando.Age = 30;

Console.WriteLine($"{expando.Name}, {expando.Age}");

using System.Dynamic;

dynamic expando = new ExpandoObject();
expando.Name = "John"; // 动态添加成员
Console.WriteLine(expando.Name); // 动态访问成员

// 等价于：
var expando = new ExpandoObject() as IDictionary<string, object>;
expando["Name"] = "John";
Console.WriteLine(expando["Name"]);

dynamic expando = new ExpandoObject();
expando.Name = "John";
expando.Age = 30;

// 删除成员
var dict = (IDictionary<string, object>)expando;
dict.Remove("Age");

// 检查成员
Console.WriteLine(dict.ContainsKey("Name")); // True
Console.WriteLine(dict.ContainsKey("Age"));  // False

dynamic expando = new ExpandoObject();
expando.Name = "John";
expando.Age = 30;

var dict = (IDictionary<string, object>)expando;
var filtered = dict.Where(kv => kv.Key.StartsWith("N"));

foreach (var kv in filtered)
{
    Console.WriteLine($"{kv.Key}: {kv.Value}");
}