struct数组的别名为int

Question

struct test
{
    char member1;
    char member2;
};

int main(void)
{
    struct test structure[] = {'h', 'i'};
    static void* p = &structure;

    printf("%i", *((int*)p));

    return 0;
}

我们都知道structure应该指向struct中第一个元素的地址.为什么通过这样取消引用它,它会返回地址本身呢？

Answer 1

您的代码表现出未定义的行为.

您正在转换structure *为键入int *和解除引用.当(大部分)大小int更大时,您正在访问离线内存.(这是一个原因,还有一些原因)

+---+---+---+---+
| h | i | ? | ? |
+---+---+---+---+
Print as int: ? ? i h if machine is little endian

In ascii coding
+---+---+---+---+
| 68| 69| ? | ? |
+---+---+---+---+
Print as int: ?? ?? 69 68

现场代码

结构的正确使用是:

struct test s1   = {'h', 'i'};
struct test s2[] = { {'t', 'o'}, {'d', 'o'} };

printf("s1   : %c, %c\n", s1.member1, s1.member2);
printf("s2[0]: %c, %c\n", s2[0].member1, s2[0].member2);
printf("s2[1]: %c, %c\n", s2[1].member1, s2[1].member2);