bitset

Bitset

A bitset stores bits (elements with only two possible values: 0 or 1, true or false, ...).

(1)构造函数

#include <iostream>       // std::cout
#include <string>         // std::string
#include <bitset>         // std::bitset
using namespace std;
int main ()
{
  bitset<16> foo;
  bitset<16> bar (0xfa2);
  bitset<16> baz (string("0101111001"));


  cout << "foo: " << foo << '\n';
  cout << "bar: " << bar << '\n';
  cout << "baz: " << baz << '\n';




  return 0;
}

输出

foo: 0000000000000000
bar: 0000111110100010
baz: 0000000101111001

(2)count()

// bitset::count
#include <iostream>       // cout
#include <string>         // string
#include <bitset>         // bitset
using namespace std;
int main ()
{
  bitset<8> foo (string("10110011"));

  cout << foo << " has ";
  cout << foo.count() << " ones and ";
  cout << (foo.size()-foo.count()) << " zeros.\n";

  return 0;
}

输出

10110011 has 5 ones and 3 zeros

(3)size()

#include <iostream>       // cout
#include <string>         // string
#include <bitset>         // bitset
using namespace std;
int main ()
{
  bitset<8> foo;
  bitset<4> bar;

  cout << "foo.size() is " << foo.size() << '\n';
  cout << "bar.size() is " << bar.size() << '\n';

  return 0;
}

输出

foo.size() is 8
bar.size() is 4

(4)test

using namespace std;
#include <iostream>       // cout
#include <string>         // string
#include <cstddef>        // size_t
#include <bitset>         // bitset

int main ()
{
  bitset<5> foo (string("01011"));

    cout << "foo contains:\n";
    for (size_t i=0; i<foo.size(); ++i)
    cout << foo.test(i) <<" ";
    cout << boolalpha<<endl;
    for (size_t i=0; i<foo.size(); ++i)
    cout << foo.test(i) <<" ";
    return 0;
}

结果

foo contains:
1 1 0 1 0
true true false true false

(5)any

using namespace std;
#include <iostream>       // cout
#include <string>         // string
#include <cstddef>        // size_t
#include <bitset>         // bitset

int main ()
{
  bitset<16> foo;

  cout << "Please, enter a binary number: ";
  cin >> foo;
  if (foo.any())
    cout << foo << " has " << foo.count() << " bits set.\n";
  else
    cout << foo << " has no bits set.\n";
  return 0;
}

输出

Please, enter a binary number: 10110
0000000000010110 has 3 bits set.

(6)none

// bitset::none
#include <iostream>       // cin, cout
#include <bitset>         // bitset
using namespace std;
int main ()
{
  bitset<16> foo;

  cout << "Please, enter a binary number: ";
  cin >> foo;

  if (foo.none())
    cout << foo << " has no bits set.\n";
  else
    cout << foo << " has " << foo.count() << " bits set.\n";

  return 0;
}

输出

Please, enter a binary number: 11010111
0000000011010111 has 6 bits set.

(7)all

// bitset::all
#include <iostream>       // cin, cout
#include <bitset>         // bitset
using namespace std;

int main ()
{
  bitset<8> foo;

  cout << "Please, enter an 8-bit binary number: ";
  cin >> foo;

  cout << boolalpha;
  cout << "all: " << foo.all() << '\n';
  cout << "any: " << foo.any() << '\n';
  cout << "none: " << foo.none() << '\n';

  return 0;
}

输出

Please, enter an 8-bit binary number: 11111111
all: true
any: true
none: false