比特数组

class BitArray
{
public:
    enum
    {
        bits_per_long = sizeof(unsigned long)*8,
    };
    
    BitArray(): array_(0) { }
    BitArray(unsigned long nr): array_(0)
    {
        reset(nr);
    }

    ~BitArray() { if (array_) delete [] array_; }

    BitArray(const BitArray& rhs)
    {
        if (rhs.array_)
        {
            array_ = new unsigned long[rhs.nr_long_];
            memcpy(array_, rhs.array_, rhs.nr_long_ * sizeof(unsigned long));
            nr_long_ = rhs.nr_long_;
            nr_bits_ = rhs.nr_bits_;
        }
    }

    BitArray& operator=(const BitArray& rhs)
    {
        if (this == &rhs)
        {
            return *this;
        }

        if (array_)
        {
            delete [] array_;
        }
            
        if (rhs.array_)
        {
            array_ = new unsigned long[rhs.nr_long_];
            memcpy(array_, rhs.array_, rhs.nr_long_ * sizeof(unsigned long));
            nr_long_ = rhs.nr_long_;
            nr_bits_ = rhs.nr_bits_;
        }
        return *this;
    }

    bool operator[](std::size_t nr)
    {
        if (nr >= nr_bits_)
            return false;

        unsigned long ret = array_[bitWord(nr)] & bitMask(nr);
        if (ret)
            return true;
        else
            return false;            
    }

    bool testBit(std::size_t nr)
    {
        return this->operator[](nr);
    }

    void setBit(unsigned long nr)
    {
        if (nr >= nr_bits_)
        {
            return;
        }

        array_[bitWord(nr)] |= bitMask(nr);
    }
    
    void clearBit(unsigned long nr)
    {
        if (nr >= nr_bits_)
        {
            return;
        }

        array_[bitWord(nr)] &= ~bitMask(nr);
    }

    void reset(unsigned long nr_bits)
    {
        if (array_)
        {
            delete [] array_;
        }

        unsigned long real_nr_bits = align(nr_bits);
        nr_long_ = getNrLong(real_nr_bits);
        array_ = new unsigned long[nr_long_];
        nr_bits_ = nr_bits;
        memset(array_, 0, nr_long_*sizeof(unsigned long));
    }

private:

    unsigned long getNrLong(unsigned long nr) { return nr/bits_per_long; }
    unsigned long align(unsigned long nr)
    {
        return (nr + (bits_per_long-1)) & (~(bits_per_long-1));
    }

    unsigned long bitWord(unsigned long nr)
    {
        return nr/bits_per_long;
    }
    
    unsigned long bitMask(unsigned long nr)
    {
        return nr%bits_per_long;
    }

    unsigned long nr_bits_;
    unsigned long nr_long_;
    unsigned long * array_;
};

使用如下，

#include <iostream>
#include <string>
#include <string.h>
#include "BitArray.h"

int main(void)
{
    BitArray a(10);
    a.setBit(1);
    cout << a[1] << endl;
    a.clearBit(1);
    cout << a[1] << endl;

    a.setBit(10);
    cout << a[10] << endl;
    
    return 0;
}