C Sharp

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Usage

Regular Expressions

Regex
Reference

using System;
using System.Text.RegularExpressions;

public class Test
{
    public static void Main ()
    {
        // Define a regular expression for repeated words.
        Regex rx = new Regex(@"\b(?<word>\w+)\s+(\k<word>)\b");

        // Define a test string.        
        string text = "The the quick brown fox  fox jumps over the lazy dog dog.";
        
        // Find match.
        Match match = rx.Match(text);

        // Iterature through captures
        foreach (Capture c in match.captures) {
           Console.WriteLine("Captured {c.Value}");
        }
    }	
}

Multithreading

Theadpool

C# has a convenient TheadPool class in the System.Threading namespace.

class TestClass {
  static void Main(string[] args) {

    int numberOfTasks = 10;
    int tasksRemaining = 10;
    // This is similar to a mutex.
    ManualResetEvent finishedHandle = new ManualResetEvent(false);
    for (int i = 0; i < numberOfTasks; i++) {
      int j = i;
      ThreadPool.QueueUserWorkItem(_ => {
        try {
          // Do something time consuming or resource intensive.
          // Do not use i here. You can use j instead.
        } catch (System.Exception e) {
          // Print Stack Trace
        } finally {
          if (Interlocked.Decrement(ref tasksRemaining) == 0) {
            finishedHandle.Set();
          }
        }
      });
    }

    // Blocking wait.
    finishedHandle.WaitOne();
  }
}

Platform Invoke

Reference
Platform Invoke (or P/Invoke) allows you to call and use C and C++ libraries from within your C# or other .NET programs.