__attribute __((__ packed__))有什么区别；和#pragma pack(1)

问题描述：

我正在将在Linux上完美运行的代码移植到Windows visual c ++.我在Linux中有以下代码:

I am porting a code which runs perfectly on Linux to windows visual c++. I have this code in Linux:

struct exif_desc
{
    uint16_t  tag;
    uint16_t  type;
    uint32_t  length;
    uint32_t  value;
}
__attribute__((__packed__));

我在Windows上遇到错误:

I am getting error on windows:

'__packed__' : undeclared identifier

我想知道是否可以使用

#pragma pack(1)

它们之间有什么区别吗?在Linux和Windows中是否可以为此属性使用任何语法?

is there any difference between them? Is there any syntax that can be used in Linux and Windows for this attribute?

答

__ attribute __ 是GCC扩展，特定于GCC(以及其他尝试与GCC兼容的编译器).

__attribute__ is a GCC extension, specific to GCC (and other compilers which attempts to be compatible with GCC).

#pragma pack 最初是Visual C ++编译器特定的扩展.如评论者所述，它也已在GCC中实现，以实现VC ++兼容性.

#pragma pack is originally a Visual C++ compiler specific extension. It has, as noted by commenters, been implemented in GCC as well for VC++ compatibility.

通常，您不能在另一个编译器中的一个编译器中使用扩展名.恰当的例子: __ attribute __ 在Visual C ++编译器中不作为扩展名存在.

Normally you can't use extensions in one compiler in another compiler. Case in point: __attribute__ doesn't exist as an extension in the Visual C++ compiler.

__attribute __((__ packed__))有什么区别；和#pragma pack(1)

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