c# 实现位图算法（BitMap）

  class BitMap
  {
    public int Length{ get{ return m_length;}
    }
    private int[] m_array;
    private int m_length;

    public BitMap(int length): this(length, false) { }

    //索引根据需求添加
    public bool this[int index]
    {
      get
      {        
        return Get(index);
      }
      set
      {
        Set(index,value); 
      }
    }

    //分配空间以容纳长度位值, 位数组中的所有值都设置为defaultValue。
    public BitMap(int length, bool defaultValue)
    {
      if (length < 0) {
        throw new ArgumentOutOfRangeException("length", "长度值不能小于0");
      }

      int arrayLength = length > 0 ? (((length - 1) / 32) + 1) : 0;
      m_array = new int[arrayLength];
      m_length = length;
  
      int fillValue = defaultValue ? unchecked(((int)0xffffffff)) : 0;
      for (int i = 0; i < m_array.Length; i++) {
        m_array[i] = fillValue;
      }
    }

    //返回位置索引处的位值。
    public bool Get(int index) {
      if (index < 0 || index >= Length) {
        throw new ArgumentOutOfRangeException("index", "索引值超出范围");
      }
      return (m_array[index / 32] & (1 << (index % 32))) != 0;
    }
  
    //将位置索引处的位值设置为value。
    public void Set(int index, bool value) {
      if (index < 0 || index >= Length) {
        throw new ArgumentOutOfRangeException("index", "索引值超出范围");
      }
  
      if (value) {
        m_array[index / 32] |= (1 << (index % 32));
      } else {
        m_array[index / 32] &= ~(1 << (index % 32));
      }
    }
  }