.NET (Core and Framework)

<br />
using System;<br />
using System.Threading;<br />
<br />
/*<br />
  Asynchronously find the smallest nontrivial factor of a positive integer,<br />
  using brute force.<br />
*/<br />
class Factorer {<br />
<br />
  public Factorer()<br />
  {<br />
    d_n = 0;<br />
    d_completed = false;<br />
    d_worker = null;<br />
    d_asr = null;<br />
  }<br />
<br />
  public void BeginWork(int n)<br />
  {<br />
    if (n < 2)<br />
      throw new ApplicationException("n must be an integer greater than 1");<br />
    d_completed = false;<br />
    d_worker = new WorkFunc(findFactor);<br />
    d_n = n;          // ASSIGNMENT (1)<br />
    d_asr = d_worker.BeginInvoke(null,null);<br />
  }<br />
<br />
<br />
  public bool Completed {<br />
    get  {<br />
      if ((! d_completed) && d_asr.IsCompleted) {<br />
        d_worker.EndInvoke(d_asr);<br />
        d_completed = true;<br />
      }<br />
      return d_completed;<br />
    }<br />
  }<br />
<br />
  /*<br />
    Return 0 if n is prime;<br />
    otherwise return a positive integer that is the smallest factor of n.<br />
  */<br />
  public int Factor {<br />
    get {<br />
      if (! Completed) {<br />
        throw new ApplicationException<br />
          ("Cannot get result before work is complete.");<br />
      }<br />
<br />
      return d_factor;<br />
    }<br />
  }<br />
<br />
  int d_n;<br />
  int d_factor;<br />
  WorkFunc d_worker;<br />
  IAsyncResult d_asr;<br />
  bool d_completed;<br />
<br />
  delegate void WorkFunc();<br />
<br />
  void findFactor()<br />
  {<br />
    int n = d_n;<br />
<br />
    if (n == 2) {<br />
      d_factor = 0;<br />
      return;<br />
    }<br />
    int u = (int) Math.Sqrt(n);<br />
    for (int i = 2; i <= u; i++) {<br />
      if ((n % i) == 0) {<br />
        d_factor = i;         // ASSIGNMENT (2)<br />
        return;<br />
      }<br />
    }<br />
    d_factor = 0;<br />
  }<br />
}<br />
<br />
<br />
class FactorMain<br />
{<br />
  public static void Main()<br />
  {<br />
    int n = 29337827;<br />
    Factorer F = new Factorer();<br />
    F.BeginWork(n);<br />
    while (! F.Completed) {<br />
      Thread.Sleep(0);<br />
    }<br />
    int d = F.Factor;<br />
    if (d == 0)<br />
      Console.WriteLine("{0} is prime");<br />
    else<br />
      Console.WriteLine("{0}={1}*{2}", n, d, n/d);<br />
  }<br />
}<br />