百思不得其解的有关问题

像下面就没有问题：#pragma pack(1)typedef struct _SYSTEMTIME {    WORD wYear;    WORD wMonth;    WORD wDayOfWeek;    WORD wDay;    WORD wHour;    WORD wMinute;    WORD wSecond;    WORD wMilliseconds;} SYSTEMTIME, *PSYSTEMTIME, *LPSYSTEMTIME;typedef struct    {        CHAR com[10];                BYTE address;//地址        CHAR mcode[10];//组别        LONG code;//编号        CHAR start_time[4];//启动时间        LONG sAfter;//累计时间        LONG acc_count;//累计数量        SYSTEMTIME dt;//日期时间    }MAINDATA;#pragma pack()extern "C" {VOID WINAPI test(MAINDATA *p){    ::ZeroMemory(p,sizeof(MAINDATA));    ::CopyMemory(p->com,"ab",2);    ::CopyMemory(p->mcode,"ab",2);    p->acc_count=21;    p->address=1;    p->code=23;    GetLocalTime(&p->dt);    p->sAfter=53;    ::CopyMemory(p->start_time,"abcd",4);    }}PB：global type str_systemtime from structure    uint wYear    uint wMonth    uint wDayOfWeek    uint wDay    uint wHour    uint wMinute    uint wSecond    uint wMillisecondsend typeglobal type str_maindata from structure    CHAR com[10];        BYTE address;//地址    CHAR mcode[10];//组别    LONG code;//编号    CHAR start_time[4];//启动时间    LONG sAfter;//累计时间    LONG acc_count;//累计数量    str_SYSTEMTIME dt;//日期时间end typesubroutine test(ref str_MAINDATA p) library "vscomm.dll" alias for "test;ansi"str_MAINDATA ptest(p)messagebox('',p.safter)当把dt改变位置其它不变就有问题，我也百思不得期解，如下:#pragma pack(1)typedef struct _SYSTEMTIME {    WORD wYear;    WORD wMonth;    WORD wDayOfWeek;    WORD wDay;    WORD wHour;    WORD wMinute;    WORD wSecond;    WORD wMilliseconds;} SYSTEMTIME, *PSYSTEMTIME, *LPSYSTEMTIME;typedef struct    {        CHAR com[10];        SYSTEMTIME dt;//日期时间        BYTE address;//地址        CHAR mcode[10];//组别        LONG code;//编号        CHAR start_time[4];//启动时间        LONG sAfter;//累计时间        LONG acc_count;//累计数量    }MAINDATA;#pragma pack()extern "C" {VOID WINAPI test(MAINDATA *p){    ::ZeroMemory(p,sizeof(MAINDATA));    ::CopyMemory(p->com,"ab",2);    ::CopyMemory(p->mcode,"ab",2);    p->acc_count=21;    p->address=1;    p->code=23;    GetLocalTime(&p->dt);    p->sAfter=53;    ::CopyMemory(p->start_time,"abcd",4);    }}PB：global type str_systemtime from structure    uint wYear    uint wMonth    uint wDayOfWeek    uint wDay    uint wHour    uint wMinute    uint wSecond    uint wMillisecondsend typeglobal type str_maindata from structure    CHAR com[10];    str_SYSTEMTIME dt;//日期时间    BYTE address;//地址    CHAR mcode[10];//组别    LONG code;//编号    CHAR start_time[4];//启动时间    LONG sAfter;//累计时间    LONG acc_count;//累计数量    end typesubroutine test(ref str_MAINDATA p) library "vscomm.dll" alias for "test;ansi"str_MAINDATA ptest(p)messagebox('',p.safter)（只要dt不是放在最后，就有问题。以前我发现顺序问题，是因为内存对齐引起的；如今加了#pragma pack(1)来强制，还会出问题，还真想不透）