C#中var和dynamic之间有什么区别？

隐式类型的局部变量– var是那些声明时未指定.NET类型明确地。在隐式类型的变量中, 编译器会在编译时从用于初始化变量的值中自动推导出变量的类型。隐式类型变量的概念在C#3.0。隐式类型变量并非旨在代替普通变量声明, 而是旨在处理某些特殊情况, 例如LINQ(语言集成查询)。

例子：

//C# program to illustrate the concept
//of the implicitly typed variable
using System;
  
class GFG {
  
     //Main method
     static public void Main()
     {
  
         //Creating and initializing
         //implicitly typed variables
         //Using var keyword
         var a = 'f' ;
         var b = "srcmini" ;
         var c = 30.67d;
         var d = false ;
         var e = 54544;
  
         //Display the type
         Console.WriteLine( "Type of 'a' is : {0} " , a.GetType());
  
         Console.WriteLine( "Type of 'b' is : {0} " , b.GetType());
  
         Console.WriteLine( "Type of 'c' is : {0} " , c.GetType());
  
         Console.WriteLine( "Type of 'd' is : {0} " , d.GetType());
  
         Console.WriteLine( "Type of 'e' is : {0} " , e.GetType());
     }
}

输出如下：

Type of 'a' is : System.Char 
Type of 'b' is : System.String 
Type of 'c' is : System.Double 
Type of 'd' is : System.Boolean 
Type of 'e' is : System.Int32

C# 4.0, 引入了一种新的类型dynamic, 称为动态类型。它用于避免编译时类型检查。编译器在编译时不检查动态类型变量的类型, 而是在运行时检查该类型。动态类型变量是使用dynamic关键字创建的。

例子：

//C# program to illustrate how to get the
//actual type of the dynamic type variable
using System;
  
class GFG {
  
     //Main Method
     static public void Main()
     {
  
         //Dynamic variables
         dynamic val1 = "srcmini" ;
         dynamic val2 = 3234;
         dynamic val3 = 32.55;
         dynamic val4 = true ;
  
         //Get the actual type of
         //dynamic variables
         //Using GetType() method
         Console.WriteLine( "Get the actual type of val1: {0}" , val1.GetType().ToString());
  
         Console.WriteLine( "Get the actual type of val2: {0}" , val2.GetType().ToString());
  
         Console.WriteLine( "Get the actual type of val3: {0}" , val3.GetType().ToString());
  
         Console.WriteLine( "Get the actual type of val4: {0}" , val4.GetType().ToString());
     }
}

输出如下：

Get the actual type of val1: System.String
Get the actual type of val2: System.Int32
Get the actual type of val3: System.Double
Get the actual type of val4: System.Boolean

以下是C#中var和dynamic关键字之间的一些区别：