C#中BitArray类

//放在CArray类中
public void GenPrimes() 
{ 
    //从索引2开始, 遍历数组
    for (int outer = 2; outer <= arr.GetUpperBound(0); outer++) 
        //每轮内层循环的起点是当前的outer+1索引处, 也就是不需要检查自身的索引
        for (int inner = outer + 1; inner <= arr.GetUpperBound(0); inner++) 
            //如果元素值为1, 表示还没有被素数检查排除, 则进行检查
            if (arr[inner] == 1) 
                if ((inner % outer) == 0) 
                    //如果可以被当前outer整除,说明该索引数字除了1和自身, 还有其他因数, 不是素数
                    arr[inner] = 0; 
} 

//放在CArray类中    
public void ShowPrimes()
{
    Console.WriteLine("素数筛选结果 :");
    for (int i = 2; i <= arr.GetUpperBound(0); i++)
        if (arr[i] == 1)
            Console.Write(i + " ");
}

static void Main()
{
    int size = 100;
    CArray primes = new CArray(size);
    for (int i = 0; i < size; i++)
        primes.Insert(1);
    primes.GenPrimes();
    primes.ShowPrimes();
    Console.ReadLine();
}

//原文代码不能直接运行, 已修正
using System;
using System.Text;
using System.Windows.Forms;

public partial class BitwiseCalculator : Form {
    public BitwiseCalculator()
    {
        InitializeComponent();
    }

    private StringBuilder ConvertBits(int val)
    {
        //掩码, 10000000 00000000 00000000 00000000
        int dispMask = 1 << 31;
        //4个8位加三个空格, 长度一共是35
        StringBuilder bitBuffer = new StringBuilder(35);
        for (int i = 1; i <= 32; i++) {
            if ((val & dispMask) == 0)
                bitBuffer.Append("0");
            else
                bitBuffer.Append("1");
            //假设输入的是-1, -1<<1后得到-2,可推出, 按位操作符, 操作的也是补码
            val <<= 1;
            if ((i % 8) == 0)
                bitBuffer.Append(" ");
        }
        return bitBuffer;
    }

    //公共计算方法
    void Calculator(string opt)
    {
        int val1 = int.Parse(tbox_num1.Text);
        int val2 = int.Parse(tbox_num2.Text);
        lab_bit1.Text = ConvertBits(val1).ToString();
        lab_bit2.Text = ConvertBits(val2).ToString();
        int result = 0;
        switch (opt) {
            case "and":
                result = val1 & val2;
                break;
            case "or":
                result = val1 | val2;
                break;
            case "xor":
                result = val1 ^ val2;
                break;
        }
        lab_resultNum.Text = result.ToString();
        lab_resultBit.Text = ConvertBits(result).ToString();
    }

    //点击按位或按钮
    private void bt_or_Click(object sender, EventArgs e)
    {
        Calculator("or");
    }
    //点击按位与按钮
    private void bt_and_Click(object sender, EventArgs e)
    {
        Calculator("and");
    }
    //点击按位异或按钮
    private void bt_Xor_Click(object sender, EventArgs e)
    {
        Calculator("xor");
    }
}

//原文代码不能运行, 已修正
using System;
using System.Text;
using System.Windows.Forms;

public partial class Digital2Binary : Form {
    public Digital2Binary()
    {
        InitializeComponent();
    }

    //按钮的点击函数
    private void ConvertButton_Click(object sender, EventArgs e)
    {
        int result;            
        result = int.Parse(InputBox.Text);
        ResultLable.Text = ConvertBits(result).ToString();
    }

    private StringBuilder ConvertBits(int val)
    {
        //掩码, 10000000 00000000 00000000 00000000
        int dispMask = 1 << 31;
        //4个8位加三个空格, 长度一共是35
        StringBuilder bitBuffer = new StringBuilder(35);
        for (int i = 1; i <= 32; i++) {
            if ((val & dispMask) == 0)
                bitBuffer.Append("0");
            else
                bitBuffer.Append("1");
            //假设输入的是-1, -1<<1后得到-2,可推出, 按位操作符, 操作的也是补码
            val <<= 1;
            if ((i % 8) == 0)
                bitBuffer.Append(" ");
        }
        return bitBuffer;
    }
}

//原文代码不能运行, 已修正
using System;
using System.Text;
using System.Windows.Forms;

public partial class Form1 : Form {
    public Form1()
    {
        InitializeComponent();
    }

    private StringBuilder ConvertBits(int val)
    {
        //掩码, 10000000 00000000 00000000 00000000
        int dispMask = 1 << 31;
        //4个8位加三个空格, 长度一共是35
        StringBuilder bitBuffer = new StringBuilder(35);
        for (int i = 1; i <= 32; i++) {
            if ((val & dispMask) == 0)
                bitBuffer.Append("0");
            else
                bitBuffer.Append("1");
            //假设输入的是-1, -1<<1后得到-2,可推出, 按位操作符, 操作的也是补码
            val <<= 1;
            if ((i % 8) == 0)
                bitBuffer.Append(" ");
        }
        return bitBuffer;
    }
    //左移
    private void bt_moveL_Click(object sender, EventArgs e)
    {
        int val = int.Parse(tbox_num.Text);
        lab_before.Text = ConvertBits(val).ToString();
        val <<= int.Parse(tbox_bitCount.Text);
        lab_after.Text = ConvertBits(val).ToString();
    }
    //右移
    private void bt_moveR_Click(object sender, EventArgs e)
    {
        int val = int.Parse(tbox_num.Text);
        lab_before.Text = ConvertBits(val).ToString();
        val >>= int.Parse(tbox_bitCount.Text);
        lab_after.Text = ConvertBits(val).ToString();
    }
    //清除文本
    private void bt_clear_Click(object sender, EventArgs e)
    {
        tbox_bitCount.Text = "";
        tbox_num.Text = "";
        lab_after.Text = "";
        lab_before.Text = "";
        tbox_num.Focus();
    }
}

BitArray BitSet = new BitArray(32); 

BitArray BitSet = new BitArray(32, true); 

byte[] ByteSet = new byte[] { 1, 2, 3, 4, 5 }; 
BitArray BitSet = new BitArray(ByteSet); 

using System;
using System.Collections;

namespace chapter6 {
    class Program {
        static void Main()
        {
            byte[] ByteSet = new byte[] { 1, 2, 3, 4, 5 };
            BitArray BitSet = new BitArray(ByteSet);
            for (int i = 0; i <= BitSet.Count - 1; i++) {
                if (i % 8 == 0)
                    Console.WriteLine();
                Console.Write(BitSet.Get(i) + " ");
            }
            Console.ReadLine();
        }
    }
}

using System;
using System.Collections;

class chapter6 {
    static void Main()
    {
        byte[] ByteSet = new byte[] { 1, 2, 3, 4, 5 };
        BitArray BitSet = new BitArray(ByteSet);
        string[] binNumber = new string[8];
        int bit = 0;
        for (int i = 0; i < BitSet.Count; i++) {
            bit = i % 8;
            if (BitSet.Get(i) == true)
                binNumber[bit] = "1";
            else
                binNumber[bit] = "0";
            //每读取八位就把binNumber数组的内容倒着输出到一行中
            if (bit == 7) {
                for (int j = 7; j >= 0; j--) {
                    Console.Write(binNumber[j]);
                }
                Console.WriteLine();
            }
        }
        Console.ReadLine();
    }
}

using System;
using System.Collections;
using System.Windows.Forms;

public partial class CheckPrimeNum : Form {
    public CheckPrimeNum()
    {
        InitializeComponent();
    }

    private void btnPrime_Click(object sender, EventArgs e)
    {
        BitArray bitSet = new BitArray(1024);
        int value = int.Parse(txtValue.Text);
        BuildSieve(bitSet);
        if (bitSet.Get(value))
            lblPrime.Text = (value + " 是素数");
        else
            lblPrime.Text = (value + " 不是素数");
    }

    private void BuildSieve(BitArray bits)
    {
        string primes = "";
        for (int i = 0; i < bits.Count; i++)
            bits.Set(i, true);
        //此处用了另一种筛选方法, 比不断从头检查到尾效率高很多            
        int bit = Convert.ToInt32(Math.Sqrt(bits.Count));
        //思路是, 外循环从2开始, 检查到全体数字个数的平方根次
        //为什么是平方根, 因为超过平方根的数, 会被内层循环的inner覆盖到, 这里比较抽象, 不理解不用死磕
        for (int outer = 2; outer <= bit; outer++)
            //内层循环, 从2开始, 直接排除inner * outer索引的数字, 因为它们相乘可以得到, 说明必然不是素数
            //由于是从2, 3, 4依次与outer乘, 直到乘到结果超过数字总数, 那么一定是排除了所有以outer为因数的数字, 剩下的就是素数了
            for (int inner = 2; inner * outer < bits.Count; inner++)
                bits.Set(inner * outer, false);
        //输出素数列表
        for (int i = 1; i < bits.Count; i++)
            if (bits.Get(i)) {
                primes += i.ToString("D4") + "  ";
            }
        txtPrimes.Text = primes;
    }
}

for (int inner = 2; inner * outer < bits.Count; inner++)
    bits.Set(inner * outer, false);