記憶體對齊規則

#include <stdio.h>#include <stdlib.h>int main(int argc, char *argv[]){    struct A{        int *a;        short b;        int c;        char d;        float e;        double f;    };    struct A a;    printf("0x%x [0,1,2,3]\n",&a.a);    printf("0x%x [4,5]\n",&a.b);    printf("0x%x [8,9,10,11] 規則1\n",&a.c);    printf("0x%x [12]\n",&a.d);    printf("0x%x [16,17,18,19] 規則1\n",&a.e);    printf("0x%x [24,25,26,27,28,29,30,31]\n",&a.f);    printf("%d\n",sizeof(struct A));    return 0;}

#include <stdio.h>#include <stdlib.h>int main(int argc, char *argv[]){    struct B{        char a;        int b;    };    struct A{        int *a;        short b;        struct B b1;        int c;        char d;        float e;        double f;    };    struct A a;    printf("0x%x [0,1,2,3]\n",&a.a);    printf("0x%x [4,5]\n",&a.b);    printf("0x%x [8] 規則2\n",&a.b1.a);    printf("0x%x [12,13,14,15]\n",&a.b1.b);    printf("0x%x [16,17,18,19] 規則1\n",&a.c);    printf("0x%x [20]\n",&a.d);    printf("0x%x [24,25,26,27] 規則1\n",&a.e);    printf("0x%x [32,33,34,35,36,37,38,39]\n",&a.f);    printf("%d\n",sizeof(struct A));    return 0;}

#include <stdio.h>#include <stdlib.h>int main(int argc, char *argv[]){    struct A{        short a;        double b;    };    struct A a;    printf("0x%x [0,1]\n",&a.a);    printf("0x%x [8,9,10,11,12,13,14,15] 規則1\n",&a.b);    printf("%d 規則3\n",sizeof(struct A));    return 0;}

#include <stdio.h>#include <stdlib.h>#pragma pack(4)int main(int argc, char *argv[]){    struct A{        short a;        short b;        double c;    };    struct A a;    printf("0x%x [0,1]\n",&a.a);    printf("0x%x [2,3] 規則4\n",&a.b);    printf("0x%x [4,5,6,7,8,9,10,11] 規則4\n",&a.c);    printf("%d 規則5\n",sizeof(struct A));    return 0;}