Introduction to C

1
Introduction to C and Visual Studio 2005

• Neng Giin (Microsoft Singapore)
• Special thanks to From Java to C A
  Developers Guide (by Mok Heng Ngee), David Lo,
  Beatrice Luca

2
Contents (1)

• Introduction to .NET and C
• C and VS 2005 examples
• Types, operators and flow controls
• Intermediate topics
• Arrays
• Exception Handling
• Delegates

3
Contents (2)

• Intermediate topics cont
• Events
• File IO
• Built in data structures
• Class, Method and Other OO Stuffs
• Cs C features Naming Conventions

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Part I

• Introduction to .Net and C

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What exactly is .NET for developers?

• New programming paradigm
• Interoperability of multiple languages
• New programming languages
• VB.Net, C.NET, VC.NET, Jscript.NET and J.NET
• New runtime environment
• JIT compilation, memory management, type safety
  checking, garbage collection, etc
• .NET Framework - Extensive selection of built-in
  class libraries (BCLs)
• Win32 API, WPF, WCF, etc.
• Other useful functionalities

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.NET Framework in Context
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Programming Paradigm

• True language interoperability
• Methods interoperability
• Inheritance
• True integrated development and debugging
  environment
• How is the support of multiple languages achieved
  ?
• MSIL - equivalent to java byte code in Java
• CLR (Common Language Runtime) - similar to JVM
• CLI (Common Language Infrastructure)

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MSIL, CLR CLI

• .NET compiles not to binary but to intermediate
  language (MSIL).
• CLR provides JIT (Just In Time) compilation to
  binary (IL is not interpreted)
• CLI standard for interoperability. Ensure
  conversion to universal MSIL.
• CTS (common type)
• CLS (common feature)

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.NET Framework Built-in Class library

• Windows specific
• Covers almost every aspect of development
• GUI, controls frames
• Networking
• Web browsing web forms
• File system access
• Windows registry access
• Database access, etc

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C, What is it - (C) ?

• C specification
• Modern, general purpose, OO
• Support SE principles
• Strong type checking
• Array bounds checking
• Automatic garbage collection
• Support development of software components in
  distributed environments
• Internationalization
• Support various types of systems

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C Extras C Java

• Combination of features of Java and C
• Similar syntax with Java with a number of minor
  exceptions
• Retains some C legacies
• Some extra features
• Indexes
• Delegates
• Etc

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C Familiar Java-like features

• Class structure
• Single inheritance
• Interfaces
• Garbage collection
• Code safety
• Stricter typing
• Etc.

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C Features in C

• Pointer operations (unsafe code)
• Operator overloading
• Preprocessor directives
• Struct
• Enum
• Etc.

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Other C Features

• Encapsulated method signatures called delegates,
  which enable type-safe event notifications.
• Properties, which serve as accessors for private
  member variables.
• Attributes, which provide declarative metadata
  about types at run time.
• Inline XML documentation comments.
• Language-Integrated Query (LINQ) which provides
  built-in query capabilities across a variety of
  data sources.

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C Vs. Java

• Feature richness Vs. Ease of use and learning
• Different purpose
• Multiple programming languages BUT single
  platform
• Single language BUT multiple platforms

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Summary Part I

• What is .Net to developers ?
• What is .Net new programming paradigm how it is
  accomplished ?
• What is C in relation to C Java ?
• - elegance simplicity of Java
• - power convenience of C

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Part II

• C VS 2005 Examples

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Simple C Program

• using System
• public class HelloWorld
• public static void Main ()
• Console.WriteLine(Hello World)

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Insertion Sort in C

• public void InsertionSort ( int array)
• for (int j2jarrayj
• int i j-1
• while (i0 arrayi key) arrayi1
  arrayi
• i i-1
• arrayi1 key

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Summary Part II

• Some simple examples of C code
• A snapshot of VS.Net environment

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Part III

• Types, operators, and flow controls

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Section 3.1

• Available Types, How to Use Them Related issues

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Cs Types Its Categories

• In C, every type, even primitive ones, can be
  treated as objects (true OO, unlike Java)
• Types are categorized to
• Pointer types used for pointer operation in
  unsafe codes
• Reference types (similar with reference type in
  java) reference to an object on the heap
• Value types (similar to simple types in java)
  int, float, short, byte

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Value Types

• bool
• decimal
• float
• double
• long
• ulong
• char

• sbyte
• byte
• short
• ushort
• int
• uint

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Decimal Type

• Unique to C
• 128 bit data type
• Range 1.010-28 till 7.91028
• Precision 28-29 significant digits
• Useful for financial or scientific calculations
  requiring precision
• Cant be converted implicitly to double or float
  (decimal have smaller range).

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String literal Types

• Two types (Regular and Verbatim)
• Regular string literal considers escape sequences
• string dir C\ -- compile error
• Verbatim string literal - add _at_ e.g. string dir
  _at_C\ -- ok
• C\ is considered as it is

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Boxing and unboxing

• Process where CLR converts simple value type to
  object
• Bridge gap between value and reference type (from
  stack to heap)
• E.g. int i 99
• object o (object) i //explicit
• i.GetType() //implicit

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Boxing and unboxing

• Different from casting, in boxing a new object is
  created
• Unboxing - Convert back to value type
• E.g.
• int i 99
• object o (object) i
• i (int) o //unboxing

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Section 3.2

• Available Operators, How to Use Them Related
  issues

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Operators
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typeof(type) operators

• Gets a representative System.Type object of a
  type or an object
• Can only be applied to type names
• Similar function can be achieved by
• Object.GetType()
• Type.GetType (string)
• E.g.
• Type t typeof (int) //System.Int32
• Type t mycarobject.GetType() // the object
  type
• Type t Type.GetType (MyClass) //MyClass

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checked unchecked keyword (1)

• checked to detect for overflow of integral
  types
• E.g.
• int i 40000
• checked
• short s (short)i
• //compiler doesnt detect overflow
• //throw overflow exception during runtime

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checked unchecked keyword (2)

• unchecked' force compilation despite detection
  of overflow at compile time
• E.g.
• unchecked
• short s1 (short) 40000
• // compiler detects overflow
• // unchecked keyword force no compile-time
  exception to be thrown.
• // during runtime, garbage value will be assigned
  to s1

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operator

• Performs like Java except for String
• Compare content of 2 strings rather than whether
  they are the same object
• E.g.
• string s1 new string (str1)
• string s2 new string (str1)
• s1s2 evaluates to false in Java, true in C

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Section 3.3

• Available Flow Controls, How to Use Them
  Related issues

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Flow Controls

• foreach
• switch-case
• goto
• break

• continue
• while
• dowhile
• for

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foreach flow control

• Repeat bunch of statements or traverse every
  element of an array/collection
• E.g.
• int array 1,2,3,4,5
• foreach (int i in array)

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switch

• Same as java except can use switch to compare
  strings
• Compulsory break at the end of every case
• fall through feature - use goto

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switch

• E.g.
• switch (car) case Volvo // do something
• goto default
• break
• case default
• // do something
• break

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goto

• Three different ways
• goto case
• goto
• goto default
• E.g.
• goto case volvo
• goto exit . exit ..

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Summary Part III

• Different types
• Different value types (more detailed look at
  Decimal)
• Boxing and unboxing
• Typeof operators
• Checked unchecked keyword
• Flow controls (more detailed look at foreach,
  goto)

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Part IV

• Intermediate Topics

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Contents

• Arrays
• Exception Handling
• Delegates
• File I/O
• Collection Classes
• Hashtable
• ArrayList

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Arrays (1)

• Single Dimensional Same as Java
• Multidimensional - two types
• Rectangular array (2D array)
• Jagged array (array of array)
• E.g.
• int MyArray1 new int 5 - single
  dimensional
• int ,MyArray2 new int 2,5 - rectangular

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Arrays (2)

• E.g. (continued)
• int MyJArray new int 2MyJArray 0
  new int 1,2,3MyJAarray 1 new int
  2,3,4,5
• int, array 1,2,3,4,5,6- initializing
  a rectangular array in a single statement
• int array new int new int
  1,2,3, new int 4,5,6,7- initializing a
  jagged array in a single statement

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Arrays (3)

• System.Array
• All array implicitly object of this class
• Contain static methods to manipulate array
• public static void Reverse (Array array)
• public static void Sort (Array array)
• public static int IndexOf (Array array, Object
  value)

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Exception Handling (1)

• Four keyword only
• try, catch, finally and throw
• No throws keyword
• All exception are unchecked exception
• You can choose not to catch them
• There wont be compile error
• Syntax the same as Java

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Exception Handling (2)

• Syntax try-catch-finally
• try
• catch (Exception e)
• finally

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Exception Handling (3)

• If not needed no need to declare exception object
  ee.g. catch (Exception)
• To re-throw the exception use catch (Exception)
  throw finally
• All exceptions are subclass of System.Exception

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C Exception Handling(4)
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Exception Handling (5)

• ApplicationException
• Thrown by user program for non-fatal error
• Derive your exception from this class
• Doesnt add new functionality
• For differentiation purpose only
• SystemException
• Thrown by CLR
• For differentiation purpose only

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Exception Handling (6)

• System. Exception Properties
• StackTrace, InnerException, Message, HelpLink,
  Source, TargetSite
• System.Exception constructors
• public Exception ()
• public Exception (string)
• public Exception (string, Exception)

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Delegates (1)

• Class derived from System.Delegate
• To encapsulate one or more methods
• When invoked, all methods it encapsulates are
  also invoked
• Behaved like a class as well a function
• Can be declared and instantiated
• Can be invoked

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Delegates (2)

• public delegate void AccDelegate (double
  increment)
• public class Car
• public void Accelerate (double increment)
• public static void Main ()
• Car c1 new Car ()
• Car c2 new Car ()
• AccDelegate a1 new AccDelegate
  (c1.Accelerate)
• AccDelegate a2 new AccDelegate
  (c2.Accelerate)
• AccDelegate commonAccelerator a1a2
  //compose
• commonAccelerator (5.5)

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Delegates (3)

• Delegate declaration
• accessibility_modif delegate return_type
  delegate_identifier (parameter list)
• E.g. public delegate void AccDelegate(double
  increment)
• - Declare a delegate that encapsulate methods
  returning void and receiving a parameter of type
  double

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Delegates (4)

• Delegate instantiation
• AccDelegate acc new AccDelegate ( c1.Accelerate
  )
• Constructor parameter (i.e. c1.Accelerate) should
  be a method with the same signature as the
  delegate
• Delegate invocation
• acc (50.0)
• c1.Accelerate () and c2.Accelerate () will be
  invoked with parameter 50.0.

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Delegates (5)

• To combine delegates simply use
• To remove simply use -
• E.g.
• MyDelegate a1 new MyDelegate (c1.Accelerate)
• MyDelegate a2 new MyDelegate (c2.Accelerate)
• MyDelegate commonAccelerator a1 a2
• commonAccelerator - a1

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File I/O (1)

• Several useful classes from System.IO namespace
• File
• Directory
• DirectoryInfo
• FileInfo
• StreamReader StreamWriter
• FileStream

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File I/O (2)

• Copying a file
• File.Copy (source, target)
• File.Copy (source, target, overwrite)
• Moving a file
• File.Move (source, target)
• Deleting a file
• File.Delete (filepath)

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File I/O (3)

• Reading a text file
• string pth _at_C\data\index.txt
• string line
• StreamReader sr new StreamReader (pth)
• while ((line sr.ReadLine())! null)
• .// do something to each line read
• sr.Close ()

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File I/O (4)

• Writing to a text file
• string pth _at_C\data\index.txt
• string line
• StreamWriter sw new StreamWriter (pth)
• sw.WriteLine (Hello World)
• sw.Write (Hello World\n)
• sw.Close()

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Collection Classes (1)

• Built in data structures
• Useful when simple array is insufficient
• A number of them
• ArrayList
• Hashtable
• BitArray,Queue,Stack,SortedList, etc
• Must import/using System.Collections

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Collection Classes (2)

• ArrayList (much like Javas Vector)
• Ordered list of objects
• Useful functions Add, Count, ToArray,
  GetEnumerator
• E.g. 1ArrayList al new ArrayList ()al.Add
  (peach)
• // add new element
• object myArray al.ToArray ()
• // ToArray returns an object array

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Collection Classes (3)

• Hashtable
• Similar to java.util.Hashtable
• Encapsulate key/value pairs
• Common functionalities
• Add
• Count
• ContainsKey
• Remove

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Collection Classes (4)

• Hashtable (cont)
• E.g. 1
• Hashtable ht new Hashtable ()
• ht.Add (A, A)
• ht.Add (B, A)
• if (ht.ContainsKey (A))
• ht.Remove (A) // removing A
• // looping through values using public property
  Values
• foreach (string val in ht.Values)
• // do some work

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Summary Part IV

• Declaration of Jagged Rectangular Array
• Exception Handling in C
• Delegates - Encapsulates list of methods
• File I/O
• StreamReader
• StreamWriter
• Useful collection classes
• Hashtable, Array List

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Part V

• Classes, methods and other OO stuffs

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Section 5.1

• Implementing Classes
• Related Issues

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Namespace

• package - in Java
• No correlation between namespace hierarchies and
  directory structure
• Eg MyNameSpace1.MyClass
• namespace MyNameSpace1 class MyClass
• Q How many namespaces can we have in a single C
  file? Can we have nested namespaces?

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Using

• import in Java
• Dont include class names in the using
• statement.
• Specify until package level only.
• Eg. using System -- OKusing System.ClassName
  -- Compile error
• using System.FakeNameSpace -- Compile error
• Q Can we have using inside a namespace?

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Using

• Can create your own alias (namespace )Eg.
• using C System.Console
• class Test
• public static void Main() C.WriteLine
  (Test)

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Common Class Modifiers

• abstract
• sealed
• public
• internal
• A class that is only accessible by code in the
  same project
• Although not the same, it is similar to package
  keyword in java
• private

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Class Members

• Data Members
• Constant
• Fields, etc.
• Function Members
• Constructor
• Method, etc.
• Some members are not available in Java.
• operator overloading, delegates, read only
  variables, etc.

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Class Inheritance

• Class Inheritance class s
• Eg.
• public class Car
• public class VolvoCar
• Q Which class has no super class?

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Implementing Interfaces

• Syntax class ,rface_2,...
• Eg.
• interface IStore
• class PetStoreIStore
• // provide concrete implementations
  for all the
• abstract methods

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Implementing Interface

• Difference from Java
• No implements keyword
• Functions declared in interface cant have any
  modifiers. Implicitly public and abstract.
• Additional notes
• Superclass listed first, followed by
  interfacesEg. public class ChildParent,I1,I2

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Abstract Sealed Classes

• Meaning are the same as their java equivalent
• Sealed
• Equivalent to java final class
• Class that cant be inherited by other class
• Abstract
• Equivalent to java abstract class
• Class that cant be instantiated

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Section 5.2

• Implementing Methods
• Related Issues

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Method Structure

• assess_modifier other_modifiers return_type
  method_name (parameter(s))
• // method code
• E.g.
• private void DoThis (int j, string s)

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Method Modifiers

• Public
• Protected
• Internal
• Private
• Sealed
• Abstract
• Static

• New
• Override
• Virtual

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ref out keyword

• Pass value type by reference instead of by value
  (! java)
• Insert ref/out in method invocation signature
  statements
• out variable no need to be initialized
• Example the ref keyword passes a reference to
  the actual double object over to the invoked
  method
• MS public void Accelerate (ref double speed)
  
• MI Accelerate (ref speed)

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Static Constructor

• Initialized static class member
• Cannot have parameters/accessibility modifiers
• Cannot be called explicitly
• Automatically invoked before the first static
  class member is utilized
• E.g.
• class Test
• static Test ()
• //initialization of static vars

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Destructor

• Called during garbage collection
• Release resources not managed by .Net runtime,
  i.e. file database connection
• E.g.
• Test()
• ...//release unneeded resources

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Constructor Initializers Chaining

• Keyword this base
• this allow the programmer to call an overloaded
  constructors in the same class
• base to call superclasss constructor
• E.g.
• public class VolvoCar
• public Volvo (string s)base (s).public
  Volvo (int i,string s)this(s).
• Chaining If none of the superclass constructors
  is explicitly invoked using base() extension,
  then the constructor of a subclass invoke the
  default constructor of the immediate superclass

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Passing Variable Number of Parameters

• params keyword (not found in Java)
• E.g. arbitrary number of int parameters
• Method definition public static void MyMethod
  (params int list)
• Method invocation MyMethod (9,24,98)
• Method behaviour list initialized to an int
  array of size 3

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Method Overloading Overriding (1)

• Overloading multiple methods of the same name
  and return type in the same class
• Same as in Java
• Constructors can be similarly overloaded
• Overriding
• Use virtual and override
• Only method declared with virtual can be
  overridden
• E.g.
• In Car (parent) public virtual void Accelerate
  ()
• In Volvo (child) public override void
  Accelerate ()

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Method Overloading Overriding (2)

• Overriding (cont)
• If no virtual and override is used, will simply
  be method hiding, not method overriding
• Although a virtual method can be overridden, it
  doesnt have to be.e.g. Virtual method is
  inherited by the subclass and can be invoked
  normally like other inherited non-virtual methods
  
• Car c1 new Car () c1.Accelerate
  ()

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Method hiding

• new keyword
• Common Use Create a new instance of class or
  struct
• As a modifier Create a new class member which
  hides an inherited member from a superclass
• E.g. public new InheritedMethod ()
• Class member cant be declared by both new and
  override

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Overriding Vs. Method hiding

• Overriding
• public class Car
• public virtual Accelerate ()
• public class VolvoCar
• public override Accelerate ()
• public static void Main()
• Volvo v new Volvo ()
• v.Accelerate() Which of the methods is called?
  
• Car c (Car) Volvo
• c.Accelerate() Which of the methods is called?
  

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Overriding Vs. Method hiding

• Method hiding
• public class Car
• public void Accelerate ()
• public class VolvoCar
• public new Accelerate ()
• public static void Main()
• Volvo v new Volvo ()
• v.Accelerate() Which of the methods is called?
• Car c (Car) Volvo
• c.Accelerate() Which of the methods is called?
  

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Constant Vs. ReadOnly

• Constant
• e.g. const char finalVar
• Read only
• e.g. readonly char finalVar
• Difference ?
• const can only be initialized on the declaration.
  Implicitly static.
• readonly can be initialized at the declaration
  and constructor. Not implicitly static.

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Summary Part V

• Import package in C
• Class structure modifiers (abstract, sealed,
  etc)
• Inheritance interface
• Method structure modifiers
• Constructors, destructors some special keywords
• Method overriding and hiding

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Part VI

• Some C Features Naming Conventions

96
Operator Overloading

• 1.09.9 - OK
• public class Fraction () Fraction f1 new
  Fraction ()Fraction f2 new Fraction
  ()f1f2 - how to do this ?
• How to extend the behaviour of operator to
  object of class Fraction?
• Use operator overloading

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Operator Overloading

• Not v. important, can be accomplished by a method
  e.g.
• f1.Add (f2) - normal public method
• Fraction.Add (f1,f2) - static method
• Intuitive appeal
• public static operator overload ()
• e.g. class Fraction
• public static Fraction operator (Fraction
  o1, Int32 o2)
• //. Other class members

98
Operator Overloading

• Operators that can be overloaded includes
• ,-,!,,,--,true,false (unary)
• - / and (binary)
• ! (comparison)
• First param type must be of the same type as the
  defining class

99
Struct

• Similar to class in syntax
• Except
• Cant be inherited
• Value type (while a class is a reference type,
  ie. stores the address of an operator)
• Can only be accessed after initialization,
  otherwise compile error
• Default constructor cant be overridden
  implicit
• No field initialization of struct data members
  i.e.struct public string Title Merchant
  // error
• No destructors

100
Struct

• E.g.
• struct Name
• private string FirstName
• public string SetFirstName (string prenom)
• public static void Main()
• Name nm new Name()
• nm.SetFirstName(John)

101
Naming Conventions

• Local Variables Method Parameters
• Camel Casing e.g. firstName, lastName, etc
• All other identifiers
• Pascal Casing e.g. MyClass, Volvo, PlainText
• Pascal Casing convention capitalizes the first
  character of each word (including acronyms over
  two letters in length) as in the following
  examples.
• PropertyDescriptor
• HtmlTag
• Camel Casing convention capitalizes the first
  character of each word except the first word, as
  in the following examples.
• propertyDescriptor
• ioStream
• htmlTag

102
Naming Conventions

• Exceptions
• Suffix with Exception
• Events
• Suffix with Events
• Event Args
• Suffix with EventArgs
• Event Handler Delegate
• Suffix with EventHandler
• Interfaces
• Prefix with I

103
Naming Convention

• Enum
• Pascal Casing for both enum identifiers and value
  names
• Namespaces
• .
• Plural nouns when appropriate
• No class have the same name as namespace
• Dont put class in BCL namespace
• Avoid words like Collections, Forms, and UI

104
Summary Part VI

• Operator overloading
• How to declare them ?
• Struct
• Similar to class with some limitations
  constraints
• Naming conventions
• Camel and Pascal Casing

105
Total Summary

• Introduction .Net C
• Simple example in C
• Class Methods in C
• Type, operator flow control available in C
• Some core topics (array, exception handling, etc)
• Cs C Features Cs coding convention

106

• Thank you for your attention