#include<stdio.h>
    //共用体类型的声明
    union Un
{
    char c;
    int i;
};
int main()
{
    union Un u;
    printf("%d\n", sizeof(u));
    printf("%d\n", sizeof(u.c));
    printf("%d\n", sizeof(u.i));

    printf("%p\n", &u);
    printf("%p\n", &(u.c));
    printf("%p\n", &(u.i));
    return 0;
}

#include<stdio.h>
union u1
{
    char ch[5];
    int i;
};
union u2
{
    short s[7];
    int i;
};
int main()
{
    printf("%d\n", sizeof(union u1));
    printf("%d\n", sizeof(union u2));
    return 0;
}

#include<stdio.h>
union u1
{
    char ch;
    int i;
};

int main()
{
    union u1 a;
    a.i = 1;
    if (a.ch == 1)
        printf("小端字节序\n");
    else
        printf("大端字节序\n");
    return 0;
}