C形式结构声明 [英] C style struct declaration

问题描述

我有关于C风格的结构的一个简单的问题。我是通过一些示例code挖掘和发现下列方式声明一个结构：

  typedef结构_STRUCTNAME
{
   //结构内容
} STRUCTNAME;
 

请注意，缺乏第二次下划线的STRUCTNAME显示出来。我的理解是，这将宣布所谓STRUCTNAME单_STRUCTNAME这种结构中没有更多的对象可以被实例化。

然而，这似乎不是这种情况。这种类型的结构从未实际上是在code实例，除了在一个地方：在这种对象的全局阵列在随机的地方使用：

  const的结构STRUCTNAME arrayName中的[] =
{
   //各种STRUCTNAMEs这里声明
};
 

再次注意缺少下划线的（我认为是实例化对象的名字吗？）

我的理解是完全关闭？

有人能解释一下吗？

解决方案

  typedef结构_STRUCTNAME
{
   //结构内容
} STRUCTNAME;
 

这件code的做了两件事：

1. 定义一个名为结构结构_STRUCTNAME 和


2. 创建一个的typedef 所谓的结构 STRUCTNAME 的。

这样做的原因是，在适当的C code，你的方式，否则声明结构（像上面的）将以下内容：

 结构_STRUCTNAME structInstance;
 

不过，与的typedef 在的地方，你可以简单地使用下列内容：

  STRUCTNAME structInstance;
 

同为枚举的声明也是如此。

I have a quick question about C style struct's. I was digging through some sample code and found a struct declared in the following way:

typedef struct _STRUCTNAME
{
   // struct contents
} STRUCTNAME;

Please note the lack of an underscore on the second time STRUCTNAME shows up. My understanding was that this would declare a single _STRUCTNAME called STRUCTNAME and no more objects of this struct could be instantiated.

However, this does not seem to be the case. A struct of this type was never actually instantiated in the code except in one place: in a global array of such objects that was used in random places:

const struct STRUCTNAME ARRAYNAME[] = 
{
   // various STRUCTNAMEs declared here
};

Note the lack of an underscore again (which I thought was the name of the instantiated object?)

Is my understanding completely off?

Could someone explain?

解决方案

typedef struct _STRUCTNAME
{
   // struct contents
} STRUCTNAME;

This piece of code does two things:

1. Defines a structure called struct _STRUCTNAME and
2. Creates a typedef of that structure called STRUCTNAME.

The reason for this is that in proper C code, the way you would otherwise declare a struct (like the above) would be the following:

struct _STRUCTNAME structInstance;

However, with the typedef in place, you can simply use the following:

STRUCTNAME structInstance;

The same holds true for enum declarations.

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