我要评论本文所述为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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