C Sharp

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.      <br />
        string text = "The the quick brown fox  fox jumps over the lazy dog dog.";
      <br />
        // 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++) {
      // Note that you cannot reuse i here.
      // You can use this trick to put it in a closure
      // Or you can make a closure manually with another anonymous function
      // i.e. (a => { return _=>{ \\ Do stuff here })(a)
      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();
  }
}

Memory Management

C# has value types and reference types. Reference types are heap allocated similar to Java. Value types are allocated either on the stack or within objects on the heap, the same as primitives in Java or structs in C/C++.

Reference types are created with classes. Value types are created with structs.

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.