C#教程之C#查找素数实现方法

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C#教程之C#查找素数实现方法

本文所述为C#查找素数的程序代码，包括了可视化窗体的代码，找素数的方法可以借鉴。虽然实现的功能简单，不过为了演示一些C#技巧，本文实例中还用到了线程技术、ListBox列表框的使用、设置程序挂起等操作，其中备有详尽的注释，帮助大家更好的理解。

具体实现代码如下：

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using System;

using System.Drawing;

using System.Collections;

using System.ComponentModel;

using System.Windows.Forms;

using System.Data;

using System.Threading;

namespace SuspendAndResume

{

 public class Form1 : System.Windows.Forms.Form

 {

 private System.Windows.Forms.Label label1;

 private System.Windows.Forms.ListBox listBox1;

 private System.Windows.Forms.Button button1;

 private System.Windows.Forms.Button button2;

 private System.Windows.Forms.Button button3;

 private System.Windows.Forms.Button button4;

 private System.Windows.Forms.Label label2;

 private System.Windows.Forms.Timer timer1;

 private System.ComponentModel.IContainer components;

 //公共委托，用于输出素数

 public delegate void UD(string returnVal);

 //声明私有线程

 private Thread pNT;

 //用于标识是否挂起线程

 bool suspend = false;

 //用于标识线程时候开始运行

 bool pNTstart = false;

 public Form1()

 {

  InitializeComponent();

  // TODO: 在 InitializeComponent 调用后添加任何构造函数代码

 }

 protected override void Dispose( bool disposing )

 {

  if( disposing )

  {

  if (components != null)

  {

   components.Dispose();

  }

  }

  base.Dispose( disposing );

 }

 #region Windows 窗体设计器生成的代码

 private void InitializeComponent()

 {

  this.components = new System.ComponentModel.Container();

  this.label1 = new System.Windows.Forms.Label();

  this.listBox1 = new System.Windows.Forms.ListBox();

  this.button1 = new System.Windows.Forms.Button();

  this.button2 = new System.Windows.Forms.Button();

  this.button3 = new System.Windows.Forms.Button();

  this.button4 = new System.Windows.Forms.Button();

  this.label2 = new System.Windows.Forms.Label();

  this.timer1 = new System.Windows.Forms.Timer(this.components);

  this.SuspendLayout();

  // label1

  this.label1.Location = new System.Drawing.Point(8, 8);

  this.label1.Name = "label1";

  this.label1.TabIndex = 0;

  this.label1.Text = "已找到的素数：";

  // listBox1

  this.listBox1.ItemHeight = 12;

  this.listBox1.Location = new System.Drawing.Point(8, 32);

  this.listBox1.MultiColumn = true;

  this.listBox1.Name = "listBox1";

  this.listBox1.Size = new System.Drawing.Size(272, 136);

  this.listBox1.TabIndex = 1;

  // button1

  this.button1.Location = new System.Drawing.Point(19, 184);

  this.button1.Name = "button1";

  this.button1.Size = new System.Drawing.Size(48, 23);

  this.button1.TabIndex = 2;

  this.button1.Text = "创建";

  this.button1.Click += new System.EventHandler(this.button1_Click);

  //

  // button2

  //

  this.button2.Location = new System.Drawing.Point(88, 184);

  this.button2.Name = "button2";

  this.button2.Size = new System.Drawing.Size(48, 23);

  this.button2.TabIndex = 3;

  this.button2.Text = "挂起";

  this.button2.Click += new System.EventHandler(this.button2_Click);

  //

  // button3

  //

  this.button3.Location = new System.Drawing.Point(157, 184);

  this.button3.Name = "button3";

  this.button3.Size = new System.Drawing.Size(48, 23);

  this.button3.TabIndex = 4;

  this.button3.Text = "恢复";

  this.button3.Click += new System.EventHandler(this.button3_Click);

  //

  // button4

  //

  this.button4.Location = new System.Drawing.Point(226, 184);

  this.button4.Name = "button4";

  this.button4.Size = new System.Drawing.Size(48, 23);

  this.button4.TabIndex = 5;

  this.button4.Text = "销毁";

  this.button4.Click += new System.EventHandler(this.button4_Click);

  //

  // label2

  //

  this.label2.Location = new System.Drawing.Point(24, 224);

  this.label2.Name = "label2";

  this.label2.Size = new System.Drawing.Size(200, 23);

  this.label2.TabIndex = 6;

  this.label2.Text = "线程未启动";

  //

  // timer1

  //

  this.timer1.Enabled = true;

  this.timer1.Tick += new System.EventHandler(this.timer1_Tick);

  //

  // Form1

  //

  this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);

  this.ClientSize = new System.Drawing.Size(292, 266);

  this.Controls.Add(this.label2);

  this.Controls.Add(this.button4);

  this.Controls.Add(this.button3);

  this.Controls.Add(this.button2);

  this.Controls.Add(this.button1);

  this.Controls.Add(this.listBox1);

  this.Controls.Add(this.label1);

  this.Name = "Form1";

  this.Text = "素数";

  this.Load += new System.EventHandler(this.Form1_Load);

  this.ResumeLayout(false);

 }

 #endregion

 /// <summary>

 /// 应用程序的主入口点。

 /// </summary>

 [STAThread]

 static void Main()

 {

  Application.Run(new Form1());

 }

 private void button1_Click(object sender, System.EventArgs e)

 {

  //创建线程实例，设置属性

  pNT = new Thread(new ThreadStart(GPN));

  pNT.Name = "Prime Numbers Exaple";

  pNT.Priority = ThreadPriority.BelowNormal;

  //设置按键，停用开始按键，启用挂起按键和销毁按键

  button1.Enabled = false;

  button2.Enabled = true;

  button4.Enabled = true;

  //线程开始，并设置标识

  pNT.Start();

  pNTstart = true;

 }

 private void button2_Click(object sender, System.EventArgs e)

 {

  //设置挂起bool变量为真

  suspend = true;

  //设置按键，停用挂起按键， 启用恢复按键

  button2.Enabled = false;

  button3.Enabled = true;

 }

 private void button3_Click(object sender, System.EventArgs e)

 {

  //设置挂起bool变量为假

  suspend = false;

  //当线程当前状态为挂起时，恢复该线程

  if(pNT.ThreadState == System.Threading.ThreadState.Suspended

  || pNT.ThreadState == System.Threading.ThreadState.SuspendRequested)

  {

  try

  {

   //恢复线程

   pNT.Resume();

   //设置按键，停用恢复按键，启用挂起按键

   button3.Enabled = false;

   button2.Enabled = true;

  }

  catch(ThreadStateException Ex)

  {

   MessageBox.Show(Ex.ToString(), "提示");

  }

  }

 }

 private void button4_Click(object sender, System.EventArgs e)

 {

  //设置按键，启用开始按键，停用其他按键

  button1.Enabled = true;

  button2.Enabled = false;

  button3.Enabled = false;

  button4.Enabled = false;

  //销毁线程

  pNT.Abort();

 }

 //GPN为GetPrimeNumber的缩写，用于查找并显示素数

 public void GPN()

 {

  //声明变量

  long Counter;  //素数个数

  long NumberNow;  //当前数

  long SqrtOfNow;  //辅助数，做数组下标

  bool IsPrime = false; //标识是否为素数

  //数组，用于存储已找到素数

  long[] PrimeArray = new long[256];

  //委托，用于显示素数，即将其添加到ListBox中

  string[] args = new string[] {"2"};

  UD UIDel = new UD(UpdateUI);

  //初始化，从3开始计算，从第2个素数开始计算

  NumberNow = 3;

  Counter = 2;

  //添加2为素数，放入素数数组并将其显示

  PrimeArray[1] = 2;

  this.Invoke(UIDel, args);

  //循环，用于找到并输出256个素数

  while(Counter <= 255)

  {

  IsPrime = true;

  //从1到当前数的平方根，穷尽计算是否为素数

  for(SqrtOfNow = 1; (PrimeArray[SqrtOfNow]

   * PrimeArray[SqrtOfNow] <= NumberNow);

   SqrtOfNow++)

  {

   //若能被已找到的素数整除，则不是素数

   if(NumberNow % PrimeArray[SqrtOfNow] == 0)

   {

   //若不是素数，跳出for循环

   IsPrime = false;

   break;

   }

  }

  //若为素数，将其添加到ListBox以显示

  if(IsPrime)

  {

   //将素数存入数组中储存

   PrimeArray[Counter] = NumberNow;

   Counter++;

   //将素数显示到ListBox中

   args[0] = NumberNow.ToString();

   this.Invoke(UIDel,args);

   //利用bool变量，控制是否挂起线程

   if( suspend == true)

   {

   //调用Suspend方法，并捕捉异常

   try

   {

    pNT.Suspend();

   }

   catch(ThreadStateException Ex)

   {

    MessageBox.Show(Ex.ToString(), "提示");

   }

   }

   //使线程睡眠，使过程清楚显示，且有时间挂起线程

   Thread.Sleep(500);

  }

  //除2外，素数必为奇数，故跳过偶数的检查，优化算法

  NumberNow += 2;

  }

 }

 //更新ListBox的方法

 void UpdateUI(string result)

 {

  listBox1.Items.Add(result);

 }

 //利用Timer控件显示线程当前状态

 private void timer1_Tick(object sender, System.EventArgs e)

 {

  //在线程开时候再获取状态并显示

  if( pNTstart )

  {

  label2.Text = "线程当前状态是：" + pNT.ThreadState.ToString();

  }

 }

 private void Form1_Load(object sender, System.EventArgs e)

 {

  //设置按键，启用开始按键，停用其他按键

  button1.Enabled = true;

  button2.Enabled = false;

  button3.Enabled = false;

  button4.Enabled = false;

 }

 }

}

感兴趣的读者可以动手调试一下该程序代码，相信会有一定的启发与借鉴价值。

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