3.位运算和位段

操作寄存器的时候比较有用，但还是很难用；

#pragma warning(disable:4996)
#include<stdio.h>
#include<string.h>
#include <stdlib.h>
struct U0
{
    unsigned int leading    : 3;
    unsigned int FLAG1        : 1;
    unsigned int FLAG2        : 1;
    unsigned int trailing    : 27;
};
void printbit(unsigned int number)
{
    unsigned mask = 1u << 31;
    for (; mask; mask >>= 1)
    {
        printf("%d",number & mask ? 1 : 0);
    }
}
int main()
{
    struct U0 uu;
    uu.leading = 2;
    uu.FLAG1 = 1;
    uu.FLAG2 = 0;
    uu.trailing = 0;
    printf("uu的大小是%d",sizeof(uu));
    printbit(*(int *)&uu);
    system("pause");
    return 0;
}