struct sizeof 结果不是预期的

2021-12-23 00:00:00 struct c++ sizeof

我有一个这样定义的结构:

I have a a struct defined thusly:

typedef struct _CONFIGURATION_DATA {
    BYTE configurationIndicator;
    ULONG32 baudRate;
    BYTE stopBits;
    BYTE parity;
    BYTE wordLength;
    BYTE flowControl;
    BYTE padding;
} CONFIGURATION_DATA;

现在，据我估计，该结构体有 10 个字节长.但是，sizeof 报告它是 16 字节长?有人知道为什么吗?

Now, by my reckoning, that struct is 10 bytes long. However, sizeof reports that it is 16 bytes long? Anyone know why?

我正在使用 Windows DDK 中的构建工具进行编译.

I am compiling using the build tools in the Windows DDK.

推荐答案

对齐.

使用

#pragma pack(1)

...结构在这里...

#pragma pack()

我还建议重新排序，如果有必要填充，然后使用 RESERVED 字节，以便多字节整数类型更好地对齐.这将使 tbe CPU 的处理速度更快，并且您的代码更小.

I would also recommend reordering things, and if necessary padding then with RESERVED bytes, so that multi-byte integral types will be better aligned. This will make processing faster for tbe CPU, and your code smaller.

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