linux c之hexdump的实现

#include 
#include 
#include 
#include 


//http://androidxref.com/7.1.1_r6/xref/external/avahi/avahi-compat-howl/text-test.c#33
static void hexdump(const void* p, size_t size) {
    const uint8_t *c = p;
    assert(p);

    printf("Dumping %u bytes from %p:\n", size, p);

    while (size > 0) {
        unsigned i;

        for (i = 0; i < 16; i++) {
            if (i < size)
                printf("%02x ", c[i]);
            else
                printf("   ");
        }

        for (i = 0; i < 16; i++) {
            if (i < size)
                printf("%c", c[i] >= 32 && c[i] < 127 ? c[i] : '.');
            else
                printf(" ");
        }

        printf("\n");

        c += 16;

        if (size <= 16)
            break;

        size -= 16;
    }
}

//默认8的倍数对齐 4+1+10=15=>16
typedef struct Person
{
    int age;
    char sex;
    char city[10];
} Person;

//默认8的倍数对齐 4+4+10=18=>24
typedef struct Student2
{
    Person* parent; //4 //存在指针到文件中的话，指针对应的数据会丢失，因为你只存储了他的地址，没有保存他的数据
    int weight;//4
    char classroom[10];//10+6
} Student2;

int main(void)
{

    Person person;
    person.age=26;
    person.sex='m';
    strcpy(person.city,"shenzhen");

     hexdump(&person,sizeof(person));

    Student2 stu;
    stu.parent=&person;//16
    stu.weight=140;
    memset(stu.classroom,0,sizeof(stu.classroom));//清零，否则是随机值
    strcpy(stu.classroom,"204");

    hexdump(&stu,sizeof(stu));

    FILE* fp=fopen("student2.struct.bin","wb");
    fwrite(&stu,sizeof(stu),1,fp);
    fclose(fp);
    printf("write_Student2_struct sizeof=%d ok!\n",sizeof(stu));//24

    printf("Hello World!\n");
    return 0;
}