CPP（八）：bitset的实现与位操作

源码如下。实现所有成员函数，实现了部分操作符重载。

#include <iostream>
using namespace std;

template <int COUNT_BITS>
class bitset
{
private:
	unsigned char *data;
	size_t cnt_bytes;
	size_t cnt_bits;
	static unsigned char mask[8];
	// 将位偏移转化为字节偏移
	int num_byte;
	int bit_pos_in_byte;
	void get_info(size_t pos)
	{
		num_byte = pos / 8;
		bit_pos_in_byte = pos % 8;
	}
	void left_shift_one_bit()
	{
		bool left_carry = test(0);
		data[0] >>= 1;
		for (size_t i = 1; i < cnt_bytes; ++i)
		{
			if (test(i * 8))
			{
				set(i * 8 - 1);
			}
			else
			{
				set(i * 8 - 1, 0);
			}
			data[i] >>= 1;
		}
		if (left_carry)
		{
			set(COUNT_BITS - 1);
		}
		else
		{
			set(COUNT_BITS - 1, 0);
		}
	}
	void right_shift_one_bit()
	{
		bool right_carry = test(COUNT_BITS - 1);
		data[cnt_bytes - 1] <<= 1;
		for (size_t i = 0; i < cnt_bytes - 1; ++i)
		{
			if (test(i * 8 + 7))
			{
				set(i * 8 + 8);
			}
			else
			{
				set(i * 8 + 8, 0);
			}
			data[i] <<= 1;
		}
		if (right_carry)
		{
			set(0);
		}
		else
		{
			set(0, 0);
		}
	}
public:
	bitset()
	{
		cnt_bytes = COUNT_BITS / 8 + 1;
		cnt_bits = COUNT_BITS % 8;
		data = new unsigned char[cnt_bytes];
		memset(data, 0, cnt_bytes);
	}
	~bitset()
	{
		delete data;
	}
	// test
	bool test(size_t pos)
	{
		get_info(pos);
		return (data[num_byte] & mask[bit_pos_in_byte]) == 0 ? false : true;
	}
	// set
	bool set(size_t pos, int value = 1)
	{
		if (pos >= COUNT_BITS) return false;
		get_info(pos);
		if (value == 1)
		{
			data[num_byte] |= mask[bit_pos_in_byte];
		}
		else
		{
			data[num_byte] &= mask[bit_pos_in_byte] ^ 0xFF;
		}
		return true;
	}
	bool set()
	{
		for (size_t i = 0; i < cnt_bytes; ++i)
		{
			data[i] = 0xFF;
		}
		return true;
	}
	// flip
	void flip()
	{
		for (size_t i = 0; i < cnt_bytes; ++i)
		{
			data[i] ^= 0xFF;// ~data[i];
		}
	}
	// count
	size_t count()
	{
		size_t cnt = 0;
		for (int i = 0; i < COUNT_BITS; ++i)
		{
			if (test(i))
			{
				++cnt;
			}
		}
		return cnt;
	}
	// any
	bool any()
	{
		for (int i = 0; i < cnt_bytes - 1; ++i)
		{
			if (data[i] > 0) return true;
		}
		for (int i = 0; i < cnt_bits; ++i)
		{
			if (data[cnt_bytes - 1] & mask[i])
			{
				return true;
			}
		}
		return false;
	}
	// none
	bool none()
	{
		return !any();
	}
	// reset
	void reset()
	{
		for (int i = 0; i < cnt_bytes; ++i)
		{
			data[i] = 0;
		}
	}
	// size
	size_t size()
	{
		return COUNT_BITS;
	}
	// to_string
	string to_string()
	{
		string str(COUNT_BITS, '0');
		for (size_t i = 0; i < COUNT_BITS; ++i)
		{
			if (test(i))
			{
				str[i] = '1';
			}
		}
		return str;
	}
	// to_ulong
	unsigned long to_ulong()
	{
		return *static_cast<unsigned long*>data;
	}
	// operator[]
	int operator[](size_t pos)
	{
		return test(pos) ? 1 : 0;
	}
	// operator<<=
	void operator<<=(size_t offset)
	{
		offset = offset % COUNT_BITS;
		for (size_t i = 0; i < offset; ++i)
		{
			left_shift_one_bit();
		}
	}
	void operator>>=(size_t offset)
	{
		offset = offset % COUNT_BITS;
		for (size_t i = 0; i < offset; ++i)
		{
			right_shift_one_bit();
		}
	}
};
template <int COUNT_BITS>
unsigned char bitset<COUNT_BITS>::mask[8] = { 1, 2, 4, 8, 16, 32, 64, 128 };

void bitset_test()
{
	bitset<11> bits;
	bits.set(3);
	for (size_t i = 0; i < 11; ++i)
	{
		if (bits.test(i))
		{
			cout << '1';
		}
		else
		{
			cout << '0';
		}
	}
	cout << endl;
	for (size_t i = 0; i < 11; ++i)
	{
		cout << bits[i];
	}
	cout << endl;
	cout << bits.to_string().c_str() << endl;
	bits.set();
	cout << bits.to_string().c_str() << endl;
	bits.set(3, 0);
	cout << bits.to_string().c_str() << endl;
	bits.flip();
	cout << bits.to_string().c_str() << endl;
	for (size_t i = 0; i < 20; ++i)
	{
		bits <<= i;
		cout << bits.to_string().c_str() << endl;
		bits >>= i;
	}

}
int main()
{
	bitset_test();
	return 0;
}