为什么无参数的Guid构造产生一个空的GUID？ [英] Why does the parameterless Guid constructor generate an empty GUID?

问题描述

为何无参数的Guid构造函数产生一个空的GUID，而不是默认生成的一个作为与Guid.NewGuid（）？

是否有一个空的Guid？

特殊用途

解决方案

  

为何无参数的Guid构造函数产生一个空的GUID，而不是默认生成的一个作为与Guid.NewGuid（）？

简短的回答：因为语言/运行时没有让Guid类型的设计者定义默认的构造函数

这不仅是传统的价值是默认构造的结构是零，你根本无法定义默认构造函数的结构。当你说新的GUID（）运行时给你，所有的字段都被初始化为它们的默认值的新对象：<一href="http://msdn.microsoft.com/en-us/library/ah19swz4%28VS.71%29.aspx">http://msdn.microsoft.com/en-us/library/ah19swz4%28VS.71%29.aspx

有些理由可以在这里找到：<一href="http://www.yoda.arachsys.com/csharp/faq/#struct.constructors">http://www.yoda.arachsys.com/csharp/faq/#struct.constructors

Why does the parameterless Guid constructor generate an empty GUID rather than default to a generated one as with Guid.NewGuid()?

Is there a particular use for an empty Guid?

解决方案

Why does the parameterless Guid constructor generate an empty GUID rather than default to a generated one as with Guid.NewGuid()?

Short answer: Because the language/runtime didn't let the designer of the Guid type define a default constructor.

It's not only conventional that the value of a "default-constructed" struct is zero, you simply cannot define a default constructor for a struct. When you say new Guid() the runtime gives you a new object where all the fields are initialized to their default values: http://msdn.microsoft.com/en-us/library/ah19swz4%28VS.71%29.aspx

Some rationale can be found here: http://www.yoda.arachsys.com/csharp/faq/#struct.constructors

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