多出的两个字节是什么啊？

[flowingfirefly]

[flowingfirefly]

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

struct date {
    char day[10];
    int month;
    int year;
};

int main() {
    struct date *object = malloc(sizeof(struct date));
    strcpy(object->day, "Good day");
    object->month = 6;
    object->year = 2013;
    printf("%d,%d,%d\n", sizeof(object->day), sizeof(object->month), sizeof(object->year));
    printf("%d\n", sizeof(struct date));
    FILE *file = fopen("output", "wb");
    if (file != NULL) {
        fwrite(object, sizeof(struct date), 1, file);
        fclose(file);
    }
    return 0;
}

[flowingfirefly]

输出： 10,4,4 20

[max_min_]

引用 2 楼 flowingfirefly 的回复:

输出： 10,4,4 20

struct date {
    char day[10];
    char res[2]; //这里多余了空余2个字节的！内存字节对齐！
                //可以google下，很基础的知识，内存对齐可以提高访问效率   
    int month;
    int year;
};

[flowingfirefly]

谢谢斑竹大人

[Adol1111]

内存对齐，看下这两篇文章就知道了 http://blog.csdn.net/mbh_1991/article/details/10241785 http://blog.csdn.net/insistGoGo/article/details/8960555