Introduction to programming using c

Introduction to programming using C#
Eng. Reham M. El-Safarini

•Outline:
2
 History.
 About C# Language.
 .NET Framework Platform Architecture.
 C# built-In types.
 Namespace & Nested Namespace.
 Object Oriented.
 Visual Studio installation.
 Hello world – First application.
 Lab work.

•History
 In concurrence with the success of java programming language, the
idea of new programming language starts to be under construction
and it’s called C#. C# is simple managed C (SMC) compiler system
unlike the C/C++ unmanaged language.
 C# means musical note such as C/C++.
 C# is an object oriented programming language which means it’s
class based and developer can apply relations such as Inheritance ,
Encapsulation and Polymorphism.
 It was released in 2000 and the project called .NET framework
3

•About C# Language
4
C# syntax is highly expressive, yet it is also simple and easy to
learn. The curly-brace syntax of C# will be instantly recognizable
to anyone familiar with C, C++ or Java. Developers who know
any of these languages are typically able to begin to work
productively in C# within a very short time. C# syntax simplifies
many of the complexities of C++ and provides powerful features
such as nullable value types, enumerations, delegates, lambda
expressions and direct memory access, which are not found in
Java. C# supports generic methods and types, which provide
increased type safety and performance, and iterators, which
enable implementers of collection classes to define custom
iteration behaviors that are simple to use by client code.

•About C# Language-Cont.
5
Language-Integrated Query (LINQ) expressions make the
strongly-typed query a first-class language construct.
As an object-oriented language, C# supports the concepts of
encapsulation, inheritance, and polymorphism. All variables and
methods, including the Main method, the application's entry
point, are encapsulated within class definitions. A class may
inherit directly from one parent class, but it may implement any
number of interfaces. Methods that override virtual methods in a
parent class require the override keyword as a way to avoid
accidental redefinition. In C#, a struct is like a lightweight class;
it is a stack-allocated type that can implement interfaces but does
not support inheritance.
In addition to these basic object-oriented principles, C# makes it
easy to develop software components through several innovative
language constructs, including the following:

•About C# Language-Cont.
6
Language-Integrated Query (LINQ) which provides built-in
query capabilities across a variety of data sources.
If you have to interact with other Windows software such as
COM objects or native Win32 DLLs, you can do this in C#
through a process called "Interop." Interop enables C#
programs to do almost anything that a native C++
application can do. C# even supports pointers and the
concept of "unsafe" code for those cases in which direct
memory access is absolutely critical.
The C# build process is simple compared to C and C++ and
more flexible than in Java. There are no separate header
files, and no requirement that methods and types be declared
in a particular order. A C# source file may define any
number of classes, structs, interfaces, and events.

•.NET Framework Platform Architecture
7
The idea behind .NET Framework is to
make a platform that can accept many languages
and then compiler will handle it.
C# programs run on the .NET Framework,
an integral component of Windows that includes
a virtual execution system called the common language
runtime (CLR) and a unified set of class libraries.
The CLR is the commercial implementation by Microsoft
of the common language infrastructure (CLI),
an international standard that is the basis for
creating execution and development environments in which
languages and libraries work together seamlessly.
Source code written in C# is compiled into an intermediate
language (IL) that conforms to the CLI specification.
The IL code and resources, such as bitmaps and strings, are stored on disk in an executable file called an
assembly, typically with an extension of .exe or .dll. An assembly contains a manifest that provides
information about the assembly's types, version, culture, and security requirements.

•.NET Framework Platform Architecture-Cont
8
When the C# program is executed, the assembly is loaded into
the CLR, which might take various actions based on the
information in the manifest. Then, if the security requirements are
met, the CLR performs just in time (JIT) compilation to convert
the IL code to native machine instructions. The CLR also
provides other services related to automatic garbage collection,
exception handling, and resource management. Code that is
executed by the CLR is sometimes referred to as "managed
code," in contrast to "unmanaged code" which is compiled into
native machine language that targets a specific system. The
following diagram illustrates the compile-time and run-time
relationships of C# source code files, the .NET Framework class
libraries, assemblies, and the CLR.

•.NET Framework Platform Architecture-Cont
9

•C# built-In types:
10
In order to define variables, developer needs to decide which
type to choose for example if you want to define a number you
need to declare a variable using int, for example:
int number = 0;
And so on.
Type variable Assig
n
Initial value
semicolon
Left hand-side Right hand-
side

•C# built-In types – Cont.:
11
It is used to declare variables to store the Boolean values, true and false.
The byte keyword denotes an integral type that stores values that ranges between 0-255, allocate size
Unsigned 8-bit integer
The char keyword is used to declare an instance of the System.Char structure that the .NET Framework
uses to represent a Unicode character. The value of a Char object is a 16-bit numeric (ordinal) value.
The byte keyword denotes an integral type that stores values that ranges between -128 to 127, allocate
size signed 8-bit integer
The decimal keyword indicates a 128-bit data type. Compared to floating-point types, the decimal type has more
precision and a smaller range, which makes it appropriate for financial and monetary calculations. The approximate
range is (-7.9 x 1028 to 7.9 x 1028) / (100 to 28) and precision for the decimal type is 28-29 significant digits
The double keyword signifies a simple type that stores 64-bit floating-point values. The precision is ±5.0 × 10−324 to
±1.7 × 10308 and approximate range for the double type is 15-16 digits.
The float keyword signifies a simple type that stores 32-bit floating-point values. The precision is 7 digits and
approximate range for the float type is -3.4 × 1038to +3.4 × 1038.
The int keyword denotes an integral type that stores values within Signed 32-bit integer size and within -
2,147,483,648 to 2,147,483,647 range
The uint keyword signifies an integral type that stores values within Unsigned 32-bit integer size and within 0 to
4,294,967,295 range
The long keyword denotes an integral type that stores values within Signed 64-bit integer size and within
9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 range
The ulong keyword denotes an integral type that stores values within Unsigned 64-bit integer size and within 0 to
18,446,744,073,709,551,615
The object type is an alias for Object in the .NET Framework. In the unified type system of C#, all types, predefined and
user-defined, reference types and value types, inherit directly or indirectly from Object. You can assign values of any
type to variables of type object
The short keyword denotes an integral data type that stores values within -32,768 to 32,767 size and within
Signed 16-bit integer range .
The ushort keyword indicates an integral data type that stores values within Unsigned 16-bit integer size
and within 0 to 65,535 range .
The string type represents a sequence of zero or more Unicode characters. string is an alias for String in
the .NET Framework.

•Namespace:
12
Namespaces are used to provide a "named space" in which your application resides. They're used especially to
provide the C# compiler a context for all the named information in your program, such as variable names. Without
namespaces, for example, you wouldn't be able to make a class named Console, as .NET already uses one in its
System namespace. The purpose of namespaces is to solve this problem, and release thousands of names defined in
the .NET Framework for your applications to use, along with making it so your application doesn't occupy names
for other applications, if your application is intended to be used in conjunction with another. So namespaces exist to
resolve ambiguities a compiler wouldn't otherwise be able to do.

•Nested Namespace:
13
Normally, your entire application resides under its own special namespace,
often named after your application or project name. Sometimes, companies
with an entire product series decide to use nested namespaces though, where
the "root" namespace can share the name of the company, and the nested
namespaces the respective project names. This can be especially convenient,
if you're a developer who has made a library with some usual functionality
that can be shared across programs. If both the library and your program
shared a parent namespace, that one would then not have to be explicitly
declared with the using keyword, and still not have to be completely typed
out. If your code was open for others to use, third party developers that may
use your code would additionally then see that the same company had
developed the library and the program. The developer of the library and
program would finally also separate all the named information in their
product source codes, for fewer headaches especially, if common names are
used.

•Object Oriented:
14
Object Oriented is a very important concept that every developer to be needs to
know. The simple type int lets you declare integer variables as shown previously in
slide 10 , and in the same way, you can create your own classes, which contain not
only data like the simple types, but methods as well. Just as you create integer
variables with the int type, so you create objects from classes. An integer variable
is an instance of the int type, just like an object is an instance of a class. Classes are
types, but are far more powerful than the simple types like int and float. Not only
can you customize your data storage using classes, but you can also add methods to
classes. That kind of compartmentalization—where data and methods are rolled up
into a single class—is the entire reason that OOP was introduced in the first place.
It enables the programmers to deal with larger programs. The process of wrapping
related data and methods into a class (and so preventing them from cluttering up
the rest of the program) to create a single entity is called encapsulation.

•Object Oriented-Cont.:
15
You create classes in C# with the class statement:
[attributes] [modifiers] class identifier [:base-list] { class-body }[;]
Here are the parts of this statement:
 attributes (Optional)—Attributes hold additional declarative information.
modifiers (Optional)—The allowed modifiers are new, static, virtual, abstract,
override, and a valid combination of the four access modifiers.
identifier—The class name. n base-list (Optional)—A list that contains the base class
and any implemented interfaces, separated by commas.
 class-body—Declarations of the class members.

•Object Oriented-Cont.:
16
Creating Objects To create an object, also called an instance, of a class,
you use the new keyword. We’ve seen how this process works; you can
see how we create a new object of the Calculator in exercise at last
slide, AddItem method to add numbers. Note the parentheses after
Calculator -highlighted with blue- in the statement
Calculator obj = new Calculator();.
These parentheses are necessary when you use the new keyword. They
let you pass data to a class’s constructor, the special method that lets
you initialize the data in a class.

•Visual Studio installation
17
Definition :
Visual studio is a Microsoft IDE(Integrated Development Environment) where a developer can install and
use to create programs.
To install VS you need to visit visualstudio and then select one of these products as shown in figure
below

•Visual Studio installation – Cont.
18
Once you click on the link, the execution file will automatically be downloaded. As
shown in figure below,

19
A wizard will launch , press continue
A waiting dialogue will start

20
Check the boxes and then press install

21
The installer will start acquiring to finally install the VS.

22
Now the installer has finished , press launch.

23
Sign in with your account, and if you don’t have one sign up for one, or you can
press Not now , maybe later. Choose your color and then press start visual studio

•Hello world
24
After successfully installing Visual studio now it’s time to create your first
application. Select File -> New -> Project as shown in figure below,

•Hello world – Cont.
25
Now select console application, and then type “Hello World” application. Then press Ok

26
Inside the main class type Console.WriteLine("Hello World"); .
Press Ctrl+F5

27
Output:

•Lab work:
28
 Description:
1.Launch VS, and then create new project.
2.The project will be building a calculator that will add,
subtract, divide and multiply numbers.
3.Apply Object oriented to the project.
Challenge : try to create windows form application.
Note: I will provide the solution next week.

•References:
 https://classes.soe.ucsc.edu/cmps020/Winter08/lectures
/intro-csharp.pdf
 https://msdn.microsoft.com/en-us/library/z1zx9t92.aspx
 https://msdn.microsoft.com/en-us/library/ya5y69ds.aspx
 https://en.wikibooks.org/wiki/C_Sharp_Programming/Na
mespaces
 http://catalogue.pearsoned.co.uk/samplechapter/067232
5470.pdf
29

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