STL-bitset

位标志只能在初始化时指定大小，后面不能再改

#include <iostream>
#include <bitset>
using namespace std;

int main(int argc, char const *argv[]) {
    bitset<4> fourbit("1011");
    cout << fourbit << endl;
    cout << "Num of 1: " << fourbit.count() << endl;

    bitset<4> fourbit2(~fourbit);
    cout << fourbit2 << endl;

    bitset<4> fourbit3 = fourbit.flip();
    cout << fourbit3 << endl;

    bitset<8> eightbit(255);
    cout << eightbit << endl;
    return 0;
}
1011
Num of 1: 3
0100
0100
11111111