对象=新的狗（）VS狗=新的狗之间的差异（） [英] Difference between object a = new Dog() vs Dog a = new Dog()

问题描述

object a = new Dog();

VS

vs

Dog a = new Dog();

在这两种情况下 a.GetType（）给狗。
都调用相同的构造（相同的层次结构）。

In both cases a.GetType() gives Dog. Both invoke same constructor (with same hierarchy).

然后可以请你告诉我，这两个语句之间的区别？

Then can you please tell me the difference between these two statements?

推荐答案

这两个创建一个Dog对象。只有第二个允许你直接调用狗的方法或以其他方式对待它像狗，例如，如果你需要将对象传递给方法作为类型的参数狗 （或东西在狗的层次结构是不是简单地对象更具体）。

Both create a Dog object. Only the second allows you to directly invoke Dog methods or to otherwise treat it like a dog, such as if you need to pass the object to a method as a parameter of type Dog (or something in the Dog hierarchy that is more specific than simply object).

object obj = new Dog(); 
// can only see members declared on object
var type = obj.GetType(); // can do this
Console.WriteLine(obj.ToString()); // also this
obj.Bark(); // Error! Bark is not a member of System.Object

Dog dog = new Dog();
// can do all of the methods declared for Object
dog.Bark(); // can finally use the method defined for Dog

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