C结构即使在正确初始化后也会打印错误的值

#include <stdio.h>

#pragma pack(push, 1)  // 禁用对齐
struct MyStruct {
    char a;
    int b;
};
#pragma pack(pop)  // 恢复默认对齐

int main() {
    struct MyStruct s = {'A', 123};
    printf("a: %c, b: %d\n", s.a, s.b);
    return 0;
}

struct MyStruct {
    char a;
    int b;
};

int main() {
    struct MyStruct s = {'A', 123};  // 显式初始化
    printf("a: %c, b: %d\n", s.a, s.b);
    return 0;
}

struct MyStruct {
    char a;
    int b;
};

int main() {
    struct MyStruct s = {'A', 123};
    struct MyStruct *ptr = &s;
    printf("a: %c, b: %d\n", ptr->a, ptr->b);
    return 0;
}

#include <stdio.h>

struct MyStruct {
    char a;
    int b;
};

int main() {
    volatile struct MyStruct s = {'A', 123};
    printf("a: %c, b: %d\n", s.a, s.b);
    return 0;
}