offsetof macro test code

最新推荐文章于 2023-09-24 23:13:47 发布

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本文详细介绍了如何使用C++结构体和指针进行数据读取，并通过实例展示了如何实现结构体成员的读取和打印。

//
#include "stdafx.h"
#include <stddef.h>

typedef int INT;
typedef unsigned char BYTE;
typedef short SHORT;

struct CubeInfo{
SHORT Volume;
INT Weight;
};

struct Cube{
BYTE no;
INT Len;
INT Width;
BYTE Height;
struct CubeInfo Info;
};

void ReadMember(BYTE *Data, struct Cube *c)
{
c->no = *(Data + offsetof(Cube, no));
c->Len = *((INT*)(Data + offsetof(Cube, Len)));
c->Width = *((INT*)(Data + offsetof(Cube, Width)));
c->Height = *((BYTE*)(Data + offsetof(Cube, Height)));

c->Info.Volume = *(SHORT*)(Data + offsetof(Cube, Info) + offsetof(CubeInfo, Volume));
c->Info.Weight = *(INT*)(Data + offsetof(Cube, Info) + offsetof(CubeInfo, Weight));
}

int _tmain(int argc, _TCHAR* argv[])
{
struct Cube cData = {1, 20, 30, 40, {50, 60}};
struct Cube c;

ReadMember((BYTE*)&cData, &c);

printf("c.no: %d\n", c.no);
printf("c.Len: %d\n", c.Len);
printf("c.Width: %d\n", c.Width);
printf("c.Height: %d\n", c.Height);
printf("c.Info.Volume: %d\n", c.Info.Volume);
printf("c.Info.Weight: %d\n", c.Info.Weight);

getchar();
return 0;
}