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：
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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