C++ 位偏移实现bitmap

#pragma once
#include <stdio.h>
#include <stdlib.h>
#include <iostream>

using namespace std;

#define BM_Max 8000000000

class BitMap
{
public:
     BitMap(unsigned);
     ~BitMap(void);

     bool getBit(unsigned);
     void setBit(unsigned);
     void resetBit(unsigned);

private:
     unsigned size;
     char* pointer;
};

 

#include "BitMap.h"


BitMap::BitMap(unsigned size)
{
     if(size < BM_Max)
     {
          this->size = size;
          unsigned byteNum = size/8 + 1;
          this->pointer = (char*)malloc(sizeof(int)*byteNum);
          for(unsigned i = 0; i < byteNum; i++){
               *(pointer+i) = 0;
          }
     }
     else
     {
          cout << "Error! Over the max size of Bit map.\n";
          exit(-1);
     }
}


BitMap::~BitMap(void)
{
     if(pointer != NULL){
          free(this->pointer);
     }
}

bool BitMap::getBit(unsigned pos)
{
     unsigned numOfchar = pos/(sizeof(char)*8);
     int restOfchar = pos%8;
     char tmp = *(this->pointer + numOfchar);
     return (tmp & (1 << restOfchar));
}

void BitMap::setBit(unsigned pos)
{
     unsigned numberOfchar = pos/(sizeof(char)*8);
     int restOfchar = pos%8;
     char tmp = *(this->pointer + numberOfchar);
     tmp |= 1 << restOfchar;
     *(this->pointer + numberOfchar) = tmp;
}

void BitMap::resetBit(unsigned pos)
{
     unsigned numberOfchar = pos/(sizeof(char)*8);
     int restOfchar = pos%8;
     char tmp = *(this->pointer + numberOfchar);
     tmp &= ~(1 << restOfchar);
     *(this->pointer + numberOfchar) = tmp;
}