C#

public void CastingCouch() {
  List<ISomeInterface> someInstances = new List<ISomeInterface>();
  someInstances.Add(new SomeClass<int>(100, 200));
  someInstances.Add(new SomeClass<string>(200, "whoop de doo"));
  someInstances.Add(new SomeClass<DateTime>(300, DateTime.Now));

  foreach (ISomeInterface reference in someInstances) {
    Console.Write("{0}  ", reference.GetType());

    if (reference is SomeClass<string>) {
      Console.WriteLine("String");
    } else if (reference is SomeClass<int>) {
      Console.WriteLine("Int");
    } else {
      Console.WriteLine("Don't know");
    }
  }
}

class SomeOtherClass : ISomeInterface { ... }
class YetAnotherClass<TKey, TValue> : ISomeInterface { ... }

someInstances.Add(new SomeOtherClass(42));
someInstances.Add(new YetAnotherClass<NotTheTypeYoureLookingFor, TheDroids>());

Type referenceType = reference.GetType();
if (referenceType.IsGenericType && referenceType.GetGenericTypeDefinition == typeof(SomeClass<>))
{
    // It's a SomeClass<T>:
    Type t = referenceType.GetGenericArguments()[0];
    ...
}
else
{
    // It's something else
}

string[] lines = File.ReadAllLines(pathToFile);

using (StreamReader read = new StreamReader(@"D:\Temp\MyBigFile.txt"))
    {
    while (read.Peek() >= 0)
        {
        string line = read.ReadLine();
        }
    }

long pos = read.BaseStream.Position;

namespace ConsoleApplication15
{
  class Program
  {
    static void Main(string[] args)
    {
      using (System.IO.StreamReader reader = new System.IO.StreamReader(@"..\..\Program.cs"))
      {
        if (reader.EndOfStream)
          return; // empty stream (also, this preloads the buffer)
        System.Console.WriteLine("Stream.Position = {0}", reader.BaseStream.Position);
      }
      System.Console.ReadLine();
    }
  }
}

Stream.Position = 455

using System;
using System.IO;

class Program
{
    static void Main()
    {
	// Read in lines from file.
	foreach (string line in File.ReadLines("c:\\file.txt"))
	{
	    Console.WriteLine("-- {0}", line);
	}
    }
}

const Int32 BufferSize = 128;
using (var fileStream = File.OpenRead(fileName))
  using (var streamReader = new StreamReader(fileStream, Encoding.UTF8, true, BufferSize)) {
    String line;
    while ((line = streamReader.ReadLine()) != null)
      // Your code goes here
      // Process line
  }

using (StreamReader reader = new StreamReader(path))
{
    string line;
    while ((line = reader.ReadLine()) != null)
    {
        yield return line;
    }
}