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Introduction of C#
Introduction of C# 15
0 Introduction of C
0 History of C
0 Design Goals
0 Why C : Features
0 C ObjectOriented Approach
0 Advantages of C
0 Applications of C
0 Introduction to .Net Framework
0 History of .Net
0 Design Features
0 .Net Architecture
0 .Net Object Oriented Approach
0 Application of .NET : GUI
0 Wrapping Up
0 References INTRODUCTION TO C
0 C is a multiparadigm programming language which is based on object
oriented and componentoriented programming disciplines.
0 It provides a framework for free intermixing constructs from different
0 It uses the “best tool for the job” since no one paradigm solves all problems in
the most efficient way. BRIEF HISTORY
0 C was developed by Microsoft with Anders Hejlsberg as the principal
designer and lead architect, within its .NET initiative and it made its
appearance in 2000.
0 Anders Hejlsberg and his team wanted to build a new programming language
that would help to write class libraries in a .NET framework. He claimed that
C was much closer to C++ in its design.
0 The name "C sharp" was inspired by musical notation where a sharp indicates
that the written note should be made a semitone higher in pitch.
0 Ever since its inception, C has controversially been stated as an imitation of
Java. However, through the course of time, both Java and C have exhibited
distinct features which support strong objectoriented design principles.
0 C was intended to be a simple, modern, objectoriented language.
0 The language and implementation had to provide support for software
engineering principles like strong type checking, array bounds checking and
automatic garbage collection.
0 The language was intended for development of software components
suitable for deployment in distributed environments.
0 Source code portability was important for programmers who were familiar
with C and C++.
0 Support for internalization to adapt the software to different languages. WHY C : FEATURES
0 C is the first “componentoriented” language in the C/C++ family.
0 The big idea of C is that everything is an object.
0 C is a programming language that directly reflects the underlying Common Language
Infrastructure (CLI). Most of its intrinsic types correspond to valuetypes implemented by
the CLI framework.
0 Typesafety: C is more type safe than C++. Type safety is the extent to which
a programming language discourages or prevents type errors.
0 C, like C++, but unlike Java, supports operator overloading.
0 Managed memory is automatically garbage collected. Garbage collection addresses the
problem of memory leaks by freeing the programmer of responsibility for releasing memory
that is no longer needed.
0 C provides properties as syntactic sugar for a common pattern in which a pair of methods,
accessor (getter) and mutator (setter) encapsulate operations on a single attribute of a
class. WHY C : FEATURES …cont.
0 In addition to the try...catch construct to handle exceptions, C has
a try...finally construct to guarantee execution of the code in
the finally block, whether an exception occurs or not.
0 Unlike Java, C does not have checked exceptions. This has been a
conscious decision based on the issues of scalability and versionability.
0 Multiple inheritance is not supported, although a class can implement any
number of interfaces. This was a design decision to avoid complication and
simplify architectural requirements throughout CLI.
0 C supports a strict Boolean data type, bool. Statements that take
conditions, such as while and if, require an expression of a type that
implements the true operator, such as the boolean type.
C OBJECT ORIENTED
(I) Structs Classes
(IV)Switch Statement: Fall Through
(V) For Each: Control Flow
(VIII)Common Type System
(I) STRUCTS CLASSES IN C
0 In C structs are very different from classes. Structs in C are designed to
encapsulate lightweight objects. They are value types (not reference types), so
they're passed by value.
0 They are sealed, which means they cannot be derived from or have any base class.
0 Classes in C are different from classes in C++ in the following ways:
i. There is no access modifier on the name of the base class and inheritance is always
ii. A class can only be derived from one base class. If no base class is explicitly
specified, then the class will automatically be derived from System.Object.
iii. In C++, the only types of class members are variables, functions, constructors,
destructors and operator overloads, C also permits delegates, events and
iv. The access modifiers public, private and protected have the same meaning as
in C++ but there are two additional access modifiers available: (a) Internal (b)
0 C does not support Multiple Inheritance
0 However a class can implement number of interfaces
0 It contains methods, properties, indexers, and events
void Bind(IDataBinder bind);
Class EditBox: Control, DataBind
void DataBind.Bind(IDataBinder bind) …
0 A delegate is similar to a function pointer in C/C.
0 Using a delegate allows a programmer to encapsulate a
reference to a method inside a delegate object, which can then
be passed to code.
0 Declaring a delegate:
public delegate void BookDelegate(Book book);
0 Instantiating a delegate:
0 Calling a delegate:
0 In C a switch statement may not "fall through" to the next statement if it does any work.
To accomplish this, you need to use an explicit goto statement:
goto case 5;
If the case statement does not work (has no code within it) then you can fall :
case 4: // fall through
(V)FOR EACH CONTROL
New control flow statement foreach :
C provides an additional flow control statement, for each. For each loops
across all items in array or collection without requiring explicit specification of
Foreach(double someElement in MyArray)
0 In C one can choose to override a virtual function from base class. Derived
method can participate in polymorphism only if it uses the keyword override before
0 In C++, if provided the same syntax method in derived class as base
class virtual method, it will be automatically be overridden.
0 In C we have abstract methods and in C++ pure virtual methods. Both may not be
exactly same, but are equivalent (as pure virtual can have function body)
public virtual string VirtualMethod()
return "base virtual";
class Derived : Base
public override string VirtualMethod()
return "Derived overriden";
(VII)BOXING AND UNBOXING
0 Boxing is the operation of converting a valuetype object into a value of a
corresponding reference type.
0 Boxing in C is implicit.
0 Unboxing is the operation of converting a value of a reference type
(previously boxed) into a value of a value type.
0 Unboxing in C requires an explicit type cast. A boxed object of type T
can only be unboxed to a T (or a nullable T).
0 EXAMPLE :
int boxvar = 42; // Value type.
object bar = boxvar; // foo is boxed to bar.
int boxvar2 = (int)bar; // Unboxed back to value type.
(VIII)COMMON TYPE SYSTEM
0 C has a unified type system. This unified type system is called Common
Type System (CTS).
0 A unified type system implies that all types, including primitives such as
integers, are subclasses of the System.Object class. For example, every type
inherits a ToString() method.
0 CTS separates data types into two categories:
1. Value types
2. Reference types
(VIII)VALUE TYPE V/S
0 Instances of value types do not have referential identity nor referential
comparison semantics i.e. equality and inequality comparisons for value types
compare the actual data values within the instances, unless the corresponding
operators are overloaded.
0 Value types are derived from System.ValueType, always have a default
value, and can always be created and copied.
0 They cannot derive from each other (but can implement interfaces) and
cannot have an explicit default (parameterless) constructor.
(VIII) VALUE TYPE VS
REFERENCE TYPE …cont.
0 Reference types have the notion of referential identity each instance of a
reference type is inherently distinct from every other instance, even if the
data within both instances is the same.
0 It is not always possible to create an instance of a reference type, nor to
copy an existing instance, or perform a value comparison on two existing
0 Specific reference types can provide services by exposing a public
constructor or implementing a corresponding interface (such
as ICloneable orIComparable). Examples: System.String, System.Array
0 Generics use type parameters, which make it possible to design classes and methods that do not
specify the type used until the class or method is instantiated.
0 The main advantage is that one can use generic type parameters to create classes and methods
that can be used without incurring the cost of runtime casts or boxing operations.
public class GenericListT
void Add(T input)
private class ExampleClass
static void Main()
// Declare a list of type int.
GenericListint list1 = new GenericListint();
// Declare a list of type string.
GenericListstring list2 = new GenericListstring();
0 Reflection is useful in the following situations:
0 When you need to access attributes in your program's metadata. See the
topic Accessing Attributes With Reflection.
0 For examining and instantiating types in an assembly.
0 For building new types at runtime. Use classes
0 For performing late binding, accessing methods on types created at run
// Using GetType to obtain type information:
int i = 42;
System.Type type = i.GetType();
ADVANTAGES OF C
0 It allows design time and run time attributes to be included.
0 It allows integrated documentation using XML.
0 No header files, IDL etc. are required.
0 It can be embedded into web pages.
0 Garbage collection ensures no memory leakage and stray pointers.
0 Due to exceptions, error handling is wellplanned and not done as an
0 Allows provision for interoperability.
APPLICATIONS OF C
0 The three main types of application that can be written in C are:
1. Winforms Windows like Forms.
2. Console Command line Input and Output.
3. Web Sites : Web sites need IIS (Microsoft's web server) and
ASP.NET. INTRODUCTION TO .NET
0 .NET framework is a software framework primarily for Microsoft Windows. It
includes a large library provides language interoperability across several
0 Programs written for the .NET Framework execute in a software environment,
as opposed to a hardware one for most other programs. Common examples of
such programs include Visual Studio, Team Explorer UI, Sharp Develop .
0 Programmers combine their own source code with the .NET Framework and
other libraries. The .NET Framework is intended to be used by most new
applications created for the Windows platform.
HISTORY OF .NET
0 .NET was developed by Microsoft in the mid 1990s, originally under the
name of ‘Next Generation Windows Services’.
0 .NET 1.1 was the first version to be included as a part of the Windows
OS. It provided builtin support for ASP .NET, ODBC Oracle
databases. It provided a higher level of trust by allowing the user to enable
Code Access Security in ASP. NET.
0 Currently, Windows 8 supports version 4.5 of .NET which supports
provision for ‘Metro Style Apps’
0 Interoperability: .NET Framework provides means to access functionality
implemented in newer and older programs that execute outside the .NET
environment. Access to COM components is provided in the
System.Runtime.InteropServices and System.EnterpriseServices
namespaces of the framework.
0 Common Language Runtime engine: CLR serves as the execution engine of
the .NET Framework. All .NET programs execute under the supervision
of the CLR, guaranteeing certain properties and behaviors in the areas of
memory management, security, and exception handling.
0 Language Independence: .NET Framework introduces Common Type
System which define all possible data types programming constructs
supported by CLR ruled for their interaction as per CLI specification.
This allows the exchange of types object instances between libraries
their applications written using any conforming .NET language.
DESIGN FEATURES …cont.
0 BCL: It is a library of functionality which is available to all languages using
the Framework. It consists of classes, interfaces or reusable types that
integrate with CLR.
0 Portability: The framework allows platformagnostic crossplatform
implementations for other OS’. The availability of specifications for the
CLI, C make it possible for third parties to create compatible
implementations of the framework it’s languages on other platforms.
ARCHITECTURE .NET ARCHITECTURE DESIGN
0 The software environment in which programs for .NET framework run is known as the ‘Common
Language Runtime’. It is Microsoft’s implementation of a ‘Common Language Infrastructure’. Its
purpose is to provide a languageneutral platform for application development execution.
0 The CLI is responsible for exception handling, garbage collection, security interoperability.
0 The CIL code is housed in CLI assemblies. The assembly consists of many files, one of which must
contain metadata for assembly.
0 An application VM provides services such as security, memory management exception handling.
0 The security mechanism supports 2 main features.
0 Code Access Security: It is based on proof that is related to a specific assembly. It uses the same to
determine permissions granted to the code.
0 Validation Verification: Validation determines whether the code satisfies specified requirements
and Verification determines whether the conditions imposed are satisfied or not. .NET ARCHITECTURE
0 The class library CLR essentially constitute the .NET Framework. The
Framework’s base class library provides UI, data access, database connectivity,
algorithms, network communications web application development.
0 In spite of the varied functionality, the BCL includes a small subset of the entire
class library is the core set of classes that serve as the basic API of the CLR.
0 The Framework Class Library is a superset of BCL refers to the entire class
library which includes libraries for ADO.NET, ASP.NET, Windows Forms,
0 It is much larger in scope compared to C++ comparable to libraries in Java.
.NET AND OBJECT
0 Memory management in .NET Framework is a crucial aspect.
0 Memory is allocated to instantiations of .NET objects from the managed
heap, a pool of memory managed by the CLR. As long as there exists a
reference to an object, either a direct reference or via a graph, the object is
considered to be in use.
0 When there is no reference to an object, and it cannot be reached or used,
it becomes garbage, eligible for collection
0 NET Framework includes a garbage collector which runs periodically, on
a separate thread from the application's thread, that enumerates all the
unusable objects and reclaims the memory allocated to them.
0 Each .NET application has a set of roots, which are pointers to objects on
the managed heap (managed objects). These may be references to static
objects, objects defined as local variables or method parameters currently in
scope, objects referred to by CPU registers
0 When the GC runs, it pauses the application, and for each object referred to
in the root, it recursively collects all the objects reachable from the root
objects and marks them as reachable.
0 It uses CLI metadata and reflection to discover the objects encapsulated by
an object, and then recursively walk them. It then enumerates all the objects on
the heap (which were initially allocated contiguously) using reflection. All
objects not marked as reachable are garbage.
The GC used by .NET Framework is actually ’generational’. Objects are
assigned a generation; newly created objects belong to ’Generation 0’. The
objects that survive a garbage collection are tagged as ’Generation 1’, and
the Generation 1 objects that survive another collection are ‘Generation
2’ objects. The .NET Framework uses up to Generation 2 objects.
GUI APPLICATIONS USING
0 Windows form is used to create applications with a user interface.
0 The following are the steps to create a Windows Form Application:
i. Open a new Project and choose the Windows Form Application
ii.Start dragging components from the Toolbox to the Form. The form will
look something like this:
GUI APPLICATIONS USING
C .NET …cont.
iii. As components are added to the Form, Visual Studio assigns default
names to each one. It is via these names that any C code will interact with the
user interface of the application.
iv. The name of these components can be changed in the Properties panel
v. In addition to changing the names of components
it is also possible to change a myriad array of
different properties via the properties panel. GUI APPLICATIONS USING
C .NET …cont.
vi. Adding behavior to a Visual Studio C application:
The next task in creating our application is to add some functionality so
that things happen when we press the two buttons in our form. This
behavior is controlled via events. For example, when a button is pressed
a Click event is triggered.
GUI APPLICATIONS USING
C .NET …cont.
0 Codes can be added for on Button Click events. Some examples are:
(I) private void closeButtonClick(object sender, EventArgs e)
(II) private void helloButtonClick(object sender, EventArgs e)
welcomeText.Text = "Hello " + nameText.Text;
ADVANTAGES OF .NET
0 Platform independent
0 Supports multiple programming languages
0 Easy to deploy
0 Supports various security features such as cryptography,
application domain, verification process etc.
0 Introduced basic concepts of C programming.
0 Discussed similarities and differences between C other
programming languages (C,C++,Java).
0 Discussed ObjectOriented behaviour of C.
0 Introduced concepts related .NET framework.
0 Explained .NET architecture.
0 Shed light upon ObjectOriented approach in .NET framework.
0 Advantages Applications of C and .NET.