BKIndex dotnet lecture01 session1 module1 2 3 4 5 operators constructs arrays

Programming in C# / Chapter 1/ 2 of 39Objectives  Explain the need for C#  Discuss flow control of a C# program  Explain the fundamental data types in C#  Discuss the concept of Boxi

Chapter 1

Programming in C# / Chapter 1/ 2 of 39

Objectives

 Explain the need for C#

 Discuss flow control of a C# program

 Explain the fundamental data types in C#

 Discuss the concept of Boxing and UnBoxing

 Discuss Structures in C#

 Discuss Enumeration types

 Compile and run a C# program

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Microsoft net

 Represents a new platform for developing

windows & web applications

 Supports more than 20 languages

 Revolutionizes facilities available for Windows programming

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Introduction to C#

 Takes full advantage of the net Platform

 The most efficient compiler in the net family

 A modern replacement for C++

 Enhances developer productivity and increases safety, by enforcing script type checking

 Allows restricted use of native pointers

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C# Program Flow

 A simple C# program:

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C# Constructs (1)

 Variables in C# are declared as follows:

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Default Values (2)

 The default values of the common data types:

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 The highlighted line acts as a placeholder where the value of the specified variable (result) will be displayed

Input / Output In C# (2)

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 The program will accept a line from the user and echo it back as output

Input / Output In C# (3)

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The switch Statement

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The while loop

 The while loop iterates through the

 The continue statement skips the current

iteration and begins with the next

iteration

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The do loop

 Syntax:

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 Syntax :

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 The foreach loop is used to iterate through a collection or an array

 Syntax:

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 Example:

 Output:

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Constructors in C#

 A constructor in C# has the same

name as

the class

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Destructors in C#

 A destructor in C# also has the same name

as the class preceded by a tilde (~)

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Fundamental Types Of C# (1)

 C# divides data types into two fundamental categories:

- int, char and structures

- classes, interfaces, arrays and strings

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 Holds a value in the memory

 Stored in a stack

 Contains the address of

the object in the heap

 = null means that no object has been

referencedFundamental Types Of C#

(2)

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Value Types

 Example:

 Output:

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Reference Types

 Example:

Output:

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Value types vs Reference types

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Boxing & Unboxing [1]

 Boxing is the conversion of a value type

into a

reference type

 Unboxing is the conversion of a reference type into a value type

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Boxing & Unboxing (2)

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Data Types In C#

 C# provides a Unified Type System

 All data types in C#, are derived from just one class, the object class

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Arrays

 A group of values of similar data type

 It belongs to the reference type and hence, are stored on the heap

 The declaration of arrays in C#, follow the syntax given below:

DataType [ number of elements ] ArrayName ;

int [ 6 ] arr1 ;

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Structures

 Custom data Types

 Can have constructors

 Cannot implement

inheritance

 Can have methods

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Enumerators (1)

 They are a set of named constants

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Enumerators (2)

 Enumerators in C# have numbers associated

with the values

 By default, the first element of enum is assigned

a value of 0 and is incremented for each

subsequent enum element

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Enumerators (3)

 The default value can be overridden during

initialization

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Compiling & Running

 Step 1 – Type your code in Notepad

 Step 2 – Save the file with a cs extension

 Step 3 – Switch to DOS prompt and type the following command: