A Brief Introduction to C

1
A Brief Introduction to C

• David Buksbaum

2
Agenda

• Goals
• Background Information
• C - Up and Running
• Quick Comparison to Java
• Networking Namespaces
• References

3
Goals

• Provide enough information to allow you to follow
  the code samples
• Highlight key differences with Java
• Tell you where you can get the compilers
• Tell you where to go for more details on C
• Tell you where to go for more detailed
  comparisons with Java
• Not to debate which is better, more important,
  faster, slower, or looks better in emacs

4
Quick Glossary

• BCL Base Class Library
• CLR Common Language Runtime
• GUI Graphic User Interface
• MSIL Microsoft Intermediate Language
• MS Microsoft
• SCM Service Control Manager
• SOA Service Oriented Architecture

5
.NET

• .NET is
• Microsofts Platform for Windows Development
• CLR the Virtual Machine that runs MSIL aka MS
  Byte Code
• BCL aka .NET Framework
• A set of compilers that can generate MSIL C,
  Visual Basic, C, Java (the MS flavor)
• There are 50 languages that generate MSIL
• http//www.dotnetpowered.com/languages.aspx
• Most interoperate with each other

6
C

• Language Created by Anders Hejlsberg (father of
  Delphi)
• The Derivation History can be viewed here
  http//www.levenez.com/lang/history.html
• Principle Influencing Languages
• C
• Delphi
• Java
• Designed to be an optimal Windows development
  language

7
C - Up and Running

• A Simple C Application
• Application Types
• Compiler Run Time

8
A Sample C Application
Code
9
Application Types

• Console Application
• Has standard streams (out, in, err)
• GUI can be added manually
• Windows Application
• GUI based
• No standard streams (out, in, err)
• Main thread is shared by the GUI message pump
  your code
• Service
• No standard streams (out, in, err)
• Main thread is commandeered by the SCM
• No GUI

10
Compiler Options from MS

• SDK contains the command line compiler
  (C\WINDOWS\Microsoft.NET\Framework\version\csc.
  exe)
• version looks like v2.0.50727
• Express Edition Free IDE to work with Visual C
• Reduced runctionality version of Visual Studio
• Visual Studio The full development system
• Optimizations, Data Access, Multi-Language, etc

11
Options Beyond MS

• Mono
• Open source development SDK for .NET
• Windows, Linux, Mac OS X, Solaris, Unix
• Sponsored by Novell
• Food for thought Suse KDE Mono ???
• Sharp Develop
• Open source IDE that uses .NET SDK or Mono
• Written in C

12
Quick Comparison to Java

• Whats the same
• Syntactically Similar
• Garbage Collected VM Environment
• Immutable Strings
• Exceptions (try / catch / finally)
• Object as root
• Single Inheritance model
• Multi-Interface model

13
Whats Different Relevant

• Keywords
• base vs. super
• lock vs. synchronized
• vs. extends implements
• is vs. instanceof
• Exceptions
• No throws keyword
• See http//msdn.microsoft.com/chats/transcripts/vs
  tudio/vstudio_032103.aspx

14
Whats Different Relevant cont.

• Namespaces
• namespace vs. package
• using vs. import
• No wildcard using
• using namespace // brings it all in
  non-recursive
• Type Aliasing
• using newtypename namespace.type
• Directory structure ! namespace hierarchy (as in
  C)

15
Whats Different Relevant cont.

• Properties
• get, set and get/set
• public string MyProperty get return(_text)
  set _text value
• Delegates
• Type safe function pointers
• To create
• public delegate bool CompareHandler(object left,
  object right)
• To use
• CompareHandler ch new CompareHandler(myMethod)
• bool retval ch(obj1, obj2)

16
Whats Different Relevant cont.

• Enumerations
• public enum Protocol UDP, TCP
• public enum Direction Up 0, Down 1, Left
  2, Right 4
• Direction d Direction.Down
• int x (int)d
• Direction d Direction.Parse(Up)
• string s d.ToString()

17
Whats Different Relevant cont.

• Value Types
• Primitives are the same plus
• Unsigned values
• ubyte, ushort, uint, ulong
• Careful byte in java is sbyte in C
• Class objects to wrap primitives
• Int32 x new Int32(4)
• int x Int32.Parse(4)

18
Whats Different Relevant cont.

• Structures
• Stack based elements, not heap based
• Value type
• struct packet int code string data
• Boxing / Unboxing
• Conversion between value type and reference type
• packet p new packet()
• object o (object)p // boxed
• packet p2 (packet)o // unboxed
• Significant performance cost!

19
Whats Different Relevant cont.

• Cross Platform Support
• .NET from Microsoft is not cross platform
• It is for Windows only
• Mono can run cross platform, but is unproven in
  large production environments
• MS is currently resisting moving cross platform
• The future is not set

20
Whats not Relevant, but Useful

• App Domains
• One or more per process
• Represents a VM hosted logical process
• Communications between App Domains requires
  marshalling (IPC)
• Assemblies
• Similar to Java JAR files
• Physically they are EXE and/or DLL files

21
Whats not Relevant, but Useful

• Attributes
• Meta tags that provide run time information for a
  type, NOT the instance
• Example Serializable public class foo int x
  
• Serializable is converted into the class
  SerializableAttribute
• Attributes can be retrieved at run time
• Many framework sub-systems use attributes
• Serialization, XML, Interop, Conditional,
  Obsolete, etc

22
Whats not Relevant, but Useful

• Polymorphism
• Methods default to being non-virtual
• To be virtual it must be defined as virtual
• eg public virtual int Add(int x, int y)
• To override a virtual method, you use the
  override keyword
• eg. public override int Add(int x, int y)
• Methods not marked virtual are equivalent to Java
  final methods
• Methods can be marked with new to break the
  virtual chain

23
Whats not Relevant, but Useful

• Interop
• Access to native code through attributes
• DllImport(user32.dll) static int
  GetSystemMetrics(int)
• The DllImport attribute informs the compiler and
  runtime that the tagged method is inside a native
  DLL.
• Options such as the actual name in the DLL,
  marshalling strategies, calling convention, and
  more can be set using the attribute

24
Whats not Relevant, but Useful

• .NET 2.0 out now
• Generics
• Partial Types
• Anonymous Methods
• Nullable Types
• .Net 3.0
• Its all about data
• Tuples Query constructs

• public void Linq1()
• int numbers 5, 4, 1, 3, 9, 8, 6, 7, 2, 0
  
• var lowNums from n in numbers where n lt 5
  select n
• Console.WriteLine("Numbers lt 5")
• foreach (var x in lowNums) Console.WriteLine(x)
  
• ResultNumbers lt 541320

25
Networking Namespaces

• System.Messaging
• Functionality for MSMQ
• System.Net
• Provides access to higher protocols (FTP, HTTP,
  DNS)
• System.Net.Information
• Network information classes providing statistics,
  interface information, and ping
• System.Net.Sockets
• Light weight wrappers around TCP and UDP sockets
• System.Runtime.Remoting
• Provides functionality for high level distributed
  programming (similar to RMI)
• System.Web
• Provides high level access to HTTP

26
Future of .NET Networking

• Windows Communications Foundation
• Formally code named Indigo
• Designed to make SOA an integral part of Windows
• Tight coupling with .NET designs
• For more information
• http//msdn.microsoft.com/windowsvista/default.asp
  x?pull/library/en-us/dnlong/html/wcfarch.asp

27
References
28
Links

• .NET SDK
• http//www.microsoft.com/downloads/details.aspx?Fa
  milyIDfe6f2099-b7b4-4f47-a244-c96d69c35decDispla
  yLangen
• MS Visual Studio C Express Edition
• http//msdn.microsoft.com/vstudio/express/visualcs
  harp/
• MS Visual Studio
• http//msdn.microsoft.com/vstudio/

29
Links cont.

• MONO
• http//www.mono-project.com/Main_Page
• Sharp Develop
• http//www.icsharpcode.net/OpenSource/SD/

30
Links cont.

• C Links
• http//msdn1.microsoft.com/en-us/default.aspx
• http//gotdotnet.com/
• http//www.c-sharpcorner.com/
• http//msdn.microsoft.com/community/codezone/
• http//en.wikipedia.org/wiki/C_Sharp_programming_l
  anguage
• Online Tutorials
• http//www.csharp-station.com/Tutorial.aspx
• http//www.c-sharpcorner.com/Tutorials.asp

31
Books

• Programming C, Fourth Edition by Jesse Liberty
  (http//search.barnesandnoble.com/booksearch/isbnI
  nquiry.asp?zyisbn0596006993itm2)
• CLR Via C Applied Microsoft .Net Framework 2.0
  Programming by Jeffrey Richter (http//search.barn
  esandnoble.com/booksearch/isbnInquiry.asp?zyisbn
  0735621632itm3)