bitset

    bitset<4> bitset1;  //无参构造,长度为4,默认每一位为0

    bitset<8> bitset2(12);  //长度为8,二进制保存,前面用0补充

    string s = "100101";
    bitset<10> bitset3(s);  //长度为10,前面用0补充

    char s2[] = "10101";
    bitset<13> bitset4(s2);  //长度为13,前面用0补充

    cout << bitset1 << endl;  //0000
    cout << bitset2 << endl;  //00001100
    cout << bitset3 << endl;  //0000100101
    cout << bitset4 << endl;  //0000000010101
    bitset<2> bitset1(12);  //12的二进制为1100(长度为4),
    //但bitset1的size=2,只取后面部分,即00

    string s = "100101";  
    bitset<4> bitset2(s);  //s的size=6,而bitset的size=4,只取前面部分,即1001

    char s2[] = "11101";
    bitset<4> bitset3(s2);  //与bitset2同理,只取前面部分,即1110

    cout << bitset1 << endl;  //00
    cout << bitset2 << endl;  //1001
    cout << bitset3 << endl;  //1110
    bitset<4> foo (string("1001"));
    bitset<4> bar (string("0011"));

    cout << (foo^=bar) << endl;       // 1010 (foo对bar按位异或后赋值给foo)
    cout << (foo&=bar) << endl;       // 0010 (按位与后赋值给foo)
    cout << (foo|=bar) << endl;       // 0011 (按位或后赋值给foo)

    cout << (foo<<=2) << endl;        // 1100 (左移2位,低位补0,有自身赋值)
    cout << (foo>>=1) << endl;        // 0110 (右移1位,高位补0,有自身赋值)

    cout << (~bar) << endl;           // 1100 (按位取反)
    cout << (bar<<1) << endl;         // 0110 (左移,不赋值)
    cout << (bar>>1) << endl;         // 0001 (右移,不赋值)

    cout << (foo==bar) << endl;       // false (0110==0011为false)
    cout << (foo!=bar) << endl;       // true  (0110!=0011为true)

    cout << (foo&bar) << endl;        // 0010 (按位与,不赋值)
    cout << (foo|bar) << endl;        // 0111 (按位或,不赋值)
    cout << (foo^bar) << endl;        // 0101 (按位异或,不赋值)
    bitset<4> foo ("1011");

    cout << foo[0] << endl;  //1
    cout << foo[1] << endl;  //1
    cout << foo[2] << endl;  //0
    bitset<8> foo ("10011011");

    cout << foo.count() << endl;  //5  
    //(count函数用来求bitset中1的位数,foo中共有5个1
    cout << foo.size() << endl;   //8  
    //(size函数用来求bitset的大小,一共有8位

    cout << foo.test(0) << endl;  //true  (
    //test函数用来查下标处的元素是0还是1,并返回false或true,此处foo[0]为1,返回true


    cout << foo.test(2) << endl;  //false  (同理,foo[2]为0,返回false

    cout << foo.any() << endl;  //true  (any函数检查bitset中是否有1
    cout << foo.none() << endl;  //false  (none函数检查bitset中是否没有1
    cout << foo.all() << endl;  //false  (all函数检查bitset中是全部为1
    bitset<8> foo ("10011011");

    cout << foo.flip(2) << endl;  //10011111  
    //(flip函数传参数时,用于将参数位取反,本行代码将foo下标2处"反转",即0变1,1变0
    cout << foo.flip() << endl;   //01100000  
    //(flip函数不指定参数时,将bitset每一位全部取反

    cout << foo.set() << endl;    //11111111  
    //(set函数不指定参数时,将bitset的每一位全部置为1
    cout << foo.set(3,0) << endl;  //11110111  
    //(set函数指定两位参数时,将第一参数位的元素置为第二参数的值,本行对foo的操作相当于foo[3]=0
    cout << foo.set(3) << endl;    //11111111  
    //(set函数只有一个参数时,将参数下标处置为1

    cout << foo.reset(4) << endl;  //11101111  
    //(reset函数传一个参数时将参数下标处置为0
    cout << foo.reset() << endl;   //00000000  
    //(reset函数不传参数时将bitset的每一位全部置为0
    bitset<8> foo ("10011011");

    string s = foo.to_string();  //将bitset转换成string类型
    unsigned long a = foo.to_ulong();  //将bitset转换成unsigned long类型
    unsigned long long b = foo.to_ullong();  //将bitset转换成unsigned long long类型

    cout << s << endl;  //10011011
    cout << a << endl;  //155
    cout << b << endl;  //155