struct对齐方式

1.对于32位操作系统：

char占1个字节	short占2个字节
int占4个字节	long占4个字节
double占8个字节	float占4个字节

2.

#include<iostream>
using namespace std;


struct A
{
int a;
char b;
short c;
};


struct B
{
char b;
int a;
short c;
};


int main()
{


    int a=sizeof(struct A);
int b=sizeof(struct B);
printf("%d\t%d\n",a,b);
return 0;
}

3.

#include<iostream>
using namespace std;


typedef union {long i; int k[5]; char c;} DATE;
struct data { int cat;  double dog;} too;
struct data2 { char cat; int dag;} tt;
struct data3 { char cat; double dag;} ;
struct data4 { char cat; DATE dag;} ;
struct data5 { char cat; unsigned short int dag;};   ？？
struct data6 { int cat; unsigned short int dag;};       ？？
struct data7 { char cat; char *dag;};
struct data8 { char cat; unsigned short int dag;int a;};
struct data9 { char cat; int a;unsigned short int x;};
struct data10 { int cat; unsigned short int dag;char a;};
void main(void)
{
  DATE max;
  printf("%d\n",sizeof(struct data));//输出16
  printf("%d\n",sizeof(struct data2));//输出8
  printf("%d\n",sizeof(struct data3));//输出16
  printf("%d\n",sizeof(struct data4));//输出24
  printf("%d\n",sizeof(struct data5));//输出4
  printf("%d\n",sizeof(struct data6));//输出8
  printf("%d\n",sizeof(struct data7));//输出8
  printf("%d\n",sizeof(struct data8));//输出8
  printf("%d\n",sizeof(struct data9));//输出12
  printf("%d\n",sizeof(struct data10));//输出8
  printf("%d\n",sizeof(struct data)+sizeof(max));//输出36
}

4.#pragma pack (2) /*指定按2字节对齐*/