class Student
{
public:
    unsigned int a:1;    //1位
    unsigned int b:1;    //1位
    unsigned int c:1;    //1位
    unsigned int d:2;    //2位
}

main(){
    qDebug()<<"a:"<<s->a;
    s->b=1;
    qDebug()<<"b:"<<s->b;
    s->c = 2;    //由于超过最大值1，所以取2(0010)的第一位0，所以结果是0
    qDebug()<<"c:"<<s->c;
    s->d = 2;
    qDebug()<<"d:"<<s->d;
    /*
    a: 0
    b: 1
    c: 0
    d: 2
    */
}