学步园

#include <iostream>

#define SIZE_TEXT 20
#pragma pack(push, 1)
class ZooMainHeader
{

//#pragma pack(push, 1)
    char        text[SIZE_TEXT];
    unsigned int        zoo_tag;
    unsigned int        zoo_start;
    unsigned int        zoo_minus;
    unsigned char      minor_ver;
    unsigned char      major_ver;
    unsigned char      type;
    unsigned char      vdata;
    unsigned int        acmt_pos;
    unsigned short        acmt_len;

//#pragma pack(pop)
    public:
    int isMainHeader()
    {
        if(zoo_tag != 0 || zoo_start + zoo_minus != 0L)
            return 0;
        return 1;
    }

    unsigned int getStrart()
    {
        return (unsigned int)zoo_start;
    }
};

int main(void)
{
    printf( "sizeof ZooMainHeader %d/n", sizeof(ZooMainHeader));
    return 0;
}

#pragma pack(pop)

以齐放在类内的类外，两种情况下，sizeof(ZooMainHeader)分类别是44（编译器做了额外2字节对齐），42

vs2008没有区别是42，