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#include <stdio.h>
#define field_offset(s,f) (int)(&(((struct s *)(0))->f))
struct AD { int a; char b[13]; double c;};
#pragma pack(push)
#pragma pack(1)
struct A1 { int a; char b[13]; double c;};
#pragma pack(2)
struct A2 { int a; char b[13]; double c;};
#pragma pack(4)
struct A4 { int a; char b[13]; double c;};
#pragma pack(8)
struct A8 { int a; char b[13]; double c;};
#pragma pack(16)
struct A16 { int a; char b[13]; double c;};
#pragma pack(pop)
int main() {
printf("AD.a %d\n",field_offset(AD,a));
printf("AD.b %d\n",field_offset(AD,b));
printf("AD.c %d\n",field_offset(AD,c));
printf("\n");
printf("A1.a %d\n",field_offset(A1,a));
printf("A1.b %d\n",field_offset(A1,b));
printf("A1.c %d\n",field_offset(A1,c));
printf("\n");
printf("A2.a %d\n",field_offset(A2,a));
printf("A2.b %d\n",field_offset(A2,b));
printf("A2.c %d\n",field_offset(A2,c));
printf("\n");
printf("A4.a %d\n",field_offset(A4,a));
printf("A4.b %d\n",field_offset(A4,b));
printf("A4.c %d\n",field_offset(A4,c));
printf("\n");
printf("A8.a %d\n",field_offset(A8,a));
printf("A8.b %d\n",field_offset(A8,b));
printf("A8.c %d\n",field_offset(A8,c));
printf("\n");
printf("A16.a %d\n",field_offset(A16,a));
printf("A16.b %d\n",field_offset(A16,b));
printf("A16.c %d\n",field_offset(A16,c));
printf("\n");
return 0;
}
//AD.a 0
//AD.b 4
//AD.c 24
//
//A1.a 0
//A1.b 4
//A1.c 17
//
//A2.a 0
//A2.b 4
//A2.c 18
//
//A4.a 0
//A4.b 4
//A4.c 20
//
//A8.a 0
//A8.b 4
//A8.c 24
//
//A16.a 0
//A16.b 4
//A16.c 24
//
//
#include "stdio.h"
struct adeal{
int a;
char *d;
};
struct adeal2{
int a;
};
struct adeal3{
char *d;
};
struct adeal4{
short int a;
char d;
};
int main(){
int a1;
short int a1_;
unsigned int a2;
long int a3;
unsigned long int a4;
float a5;
double a6;
char a7;
char *a8=&a6;
struct adeal a9;
struct adeal2 a10;
struct adeal3 a11;
struct adeal4 a12;
printf("整型长度:%d\n",sizeof(a1));
printf("短整型长度:%d\n",sizeof(a1_));
printf("无符号整型长度:%d\n",sizeof(a2));
printf("长整型长度:%d\n",sizeof(a3));
printf("无符号长整型长度:%d\n",sizeof(a4));
printf("浮点型长度:%d\n",sizeof(a5));
printf("双精度长度:%d\n",sizeof(a6));
printf("字符型长度:%d\n",sizeof(a7));
printf("字符型指针长度:%d\n",sizeof(a8));
printf("结构的长度:%d\n",sizeof(a9));
printf("结构的长度:%d\n",sizeof(a10));
printf("结构的长度:%d\n",sizeof(a11));
printf("结构的长度:%d\n",sizeof(a12));
return 1;
}
参阅sizeof用法 <a href="http://www.maomao365.com/?p=2809" target="_blank">http://www.maomao365.com/?p=2809</a>
#pragma pack(push, 1)
struct node{
int a;
char b;
unsigned short k[3];
unsigned int q;
}test1;
#pragma pack(pop)