Intro Week 2

Introducing C#

Compiled vs interpreted languages.

Which is faster?

Reading a book a line at a time.

Reading a book a page at a time.

An interpreted language reads every line every time as the program runs the interpretor executes each line it reads. A compiled language is compiles the lines of code into and executable that can be run.

Visual Studio

Projects (.prj) and Solutions (.sln, .sou)

A Visual Studio Solution contains 1 or more projects.

http://msdn.microsoft.com/en-us/library/xhkhh4zs.aspx

A project contains files needed to build the project.

Fiel types for c# and vb.net solutions

Logic Diagramming

Common Programming Language Tip excercise

Drawing Excercise

pseudo code

http://commons.wikimedia.org/wiki/Logic_diagram

Demo in viseo

Everything is an Object

In c# everything is an object. And all objects inherit from the object class.

See object in the classbrowser

Since all objects inherit from the object class they all have some the basic functionality like a method called ToString();

See the source for object.cs from mono

Basic Data Types

C# is a strongly typed language. This means every object in C# must be declared to be of a specific type. All of c# basic varible type inherit from System.Object

Variable Types

.NET Types

Type	Size in Bytes	.Net Type	Description
byte	1	Byte	Unsigned (0-255)
char	2	Char	Unicode Characters ascii unicode and other
bool	1	Boolean	True of False (Note: C# boolean values do not equate to integer values, or True != (read as is not equal to) 1 and False != 0)
sbyte	1	SByte	Signed integers(-128 to 127)
short	2	Int16	Signed integers(-32,768 to 32,767)
ushort	2	UInt16	Unsigned integers(0 to 65,535)
int	4	Int32	Signed integers(-2,147,483,648 to 2,147,483,647)
uint	4	UInt32	Unsigned integers(0 to 4,294,967,295)
float	4	Single	fixed-precision up to 7 digits. Floating point number ( 1.5 x 10-45 to 3.4 x 1038 )
double	8	Double	fixed-precision up to 16 digits. Floating point number ( 5.0 x 10-324 to 1.7 x 10308 )
decimal	12	Decimal	fixed-precision up to 28 digits. Typically used for financial calculations. Required the suffix "m" or "M"
long	8	Int64	Signed integer ( -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807)
ulong	8	UInt64	Unsigned integer (0 to 18,446,744,073,709,551,615 )

Variables must be declared with an identifier and then initialized.

Declaration

Declaration sets aside a named section of memory the is the proper size to hold the declared type. At this point the variable contains nothing.

<csharp>// declare a variable int firstInt; //declares a vaiable of type int string myString; //declares a vaiable of type string</syntaxhighlight>

Initialization

Initialization actually sets the variables value

<csharp>// initialize the variable firstInt = 1; myString = "Hello!";</syntaxhighlight>

Initialization uses the assignment operator to set the value of a variable

Assignment

The Assignment operator in c# is the '=' sign. You can assign variables like this...

Assignment

The Assignment operator in c# is the '=' sign. You can assign variables like this... We'll learn more about operators later.

other ways to do it

<csharp>// declare some variables int secondInt, thirdInt, fourthInt; secondInt = 2; thirdInt = 3; fourthInt = 4;

//declare and initialize variables in one line int myNegativeInt = -2147483648;</syntaxhighlight>

In c# variables cannot be used unil they are initialized. For example

Branching

evil goto - I won't show it figure it out on your own...

• if
• switch

Looping

• for
• while
• do... while
• foreach

Branching Statements

if

syntax

<csharp>if (expression)

   // statement
   

if (expression) {

   // statements
   // statements

} if (expression) {

   // statements
   // statements

} else {

   // statements

}</syntaxhighlight>

About braces and indenting. I usually use BSD/Allman Style.
Jargon File
indent style n.
The One True Brace Style

  Console Input
  There are several ways to get data into your program. One of the simplest is to have someone type it into the console.
  The frame work supports Console.ReadLine() this method reads on line from the input of the console.

  EchoOnce.cs

  Another popular way to get data into your program is to send it in as an argument when the program is run.

  HelloName.cs

  HelloNameSafe.cs

Homework

Programming Assignment – Number Add Write the logic diagram to obtain 3 numbers from the user and then display the sum of the three numbers.

Code a C# console application from your logic diagram.