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

Chapter 1


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
Programming in C# /
 Compile and run a C# program
Chapter 1/ 2 of 39


Microsoft .net

 Represents a new platform for developing
windows & web applications.
 Supports more than 20 languages.
 Revolutionizes facilities available for Windows
programming.
Programming in C# /
Chapter 1/ 3 of 39


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.

Programming in C# /
Chapter 1/ 4 of 39


C# Program Flow
 A simple C# program:

Programming in C# /
Chapter 1/ 5 of 39


C# Constructs (1)
 Variables in C# are declared as follows:

Programming in C# /
Chapter 1/ 6 of 39


C# Constructs (2)
 If you want to use any keyword as the
variable name, you have to prefix the
variable name with @.

Programming in C# /
Chapter 1/ 7 of 39

Default Values (1)
 Variables in C# are automatically
assigned a
default value upon creation.

 Output:
Programming in C# /
Chapter 1/ 8 of 39


Default Values (2)
 The default values of the common data types:

Programming in C# /
Chapter 1/ 9 of 39


Input / Output In C# (1)
 Uses methods of the Console class in the
System namespace.
 The most widely used methods are:

Programming in C# /
Chapter 1/ 10 of 39


Input / Output In C# (2)

 The highlighted line acts as a placeholder where
Programming

in C#will
/ be
the value of the specified variable
(result)
Chapter 1/ 11 of 39
displayed.


Input / Output In C# (3)

 The program will accept a line from the user and
Programming in C# /
echo it back as output.
Chapter 1/ 12 of 39


The if construct
 Performs conditional branching.
 Syntax :

 The expression always requires to
Programming in C# /
evaluate to
Chapter 1/ 13 of 39
an expression of Boolean type.


Selection Statement

 The above piece of code will display an

error message:
Error CS0029 : Cannot implicitly convert type 'int' to 'bool'
Programming in C# /
Chapter 1/ 14 of 39


The switch Statement
(1)
 The switch statement can be used in place
of
multiple if statements
 Syntax:

Programming in C# /
Chapter 1/ 15 of 39


The switch Statement
(2)
 Example:

 It is mandatory to specify a break
statement
Programming
in C# /
Chapter 1/ 16 of 39
for each and every case block.


Iteration

Constructs
 Performs
a certain set of instructions a
certain
number of times or while a specific
 condition
Types of iteration constructs:
is true.

Programming in C# /
Chapter 1/ 17 of 39


The while loop
 The while loop iterates through the
specified
statements
till the specified condition is
 Syntax
:
true.
 The break statement breaks out of the loop at
anytime.
 The continue statement skips
the current
Programming
in C# /
iteration and begins with the
next
Chapter

1/ 18 of 39
iteration.


The do loop
 Syntax:

Programming in C# /
Chapter 1/ 19 of 39


The for loop
 Syntax :

Programming in C# /
Chapter 1/ 20 of 39


The foreach loop (1)
 The foreach loop is used to iterate through a
collection or an array.
 Syntax:

Programming in C# /
Chapter 1/ 21 of 39


The foreach loop (2)
 Example:

 Output:
Programming in C# /
Chapter 1/ 22 of 39


Constructors in C#
 A constructor in C# has the same
name as
the class.

Programming in C# /
Chapter 1/ 23 of 39


Destructors in C#
 A destructor in C# also has the same name
as the class preceded by a tilde (~).

Programming in C# /
Chapter 1/ 24 of 39


Fundamental Types Of C#
(1)
 C# divides data types into two fundamental
categories:

- int, char and structures

- classes, interfaces, arrays and strings

Programming in C# /
Chapter 1/ 25 of 39