c++结构体内存对齐基本概念及示例

#include 

using namespace std;

#pragma pack(8)
struct Test1
{
 char a; //0 - 1
 short b;//2 - 3
 int c;// 4 - 7
 float d;//8 - 11
 double e;//12 - 23
};

#pragma pack(4)
struct Test2
{
 char a; //0 - 1
 short b;//2 - 3
 int c;// 4 - 7
 float d;//8 - 11
 double e;//12 - 19
};

#pragma pack(8)
struct Test3
{
 double e;//0-7
 float d;//8-13
 short b;//14-15
 int c;// 16-19
 char a; //20-23
};

int main()
{
 std::cout <<"size test1= " <
            var cpro_id = "u6885494";