11

Getting Started with C#

Chapter 1

22

Objectives

You will be able to:1. Say in general terms how C# differs from C.2. Create, compile, and run a very simple

Windows console application in C# using Visual Studio 2008.

33

Introduction to C#

C# is an extension of ANSI CSimilar to JavaMicrosoft Specific (Sort of)

Technically an ECMA Standard

Adds strong typing.

Adds object oriented programming constructs.Classes, Inheritance, Polymorphism

Takes away “dangerous” or error prone features.Pointers, malloc, explicit memory deallocationNo concept of “memory address”“References” serve the purpose of pointers.

Provides automatic, transparent garbage collection

Lots of useful code in libraries

44

Introduction to C#

Targeted to Microsoft platforms Specifically to the .NET framework PC applications for Windows Web applications for Microsoft web servers

Both GUI and console applications are possible.

An open source, cross-platform implementation of .NET Framework, Mono, is available:http://www.mono-project.com

55

Introduction to C#

Supported by the Visual Studio IDE Very easy to do simple GUI applications

Comparable to Visual Basic Possible to do large complex PC applications

We will use Visual Studio 2008 Available on all College of Engineering and

CSE lab and classroom computers. Free download available for USF students.

https://www.dreamspark.com

66

Introduction to C#

A Quick Look at Programming in C# (Changes and additions to standard C)

Start with Console applications. Run from a command window (No GUI) Simplest possible C# programs Get started with object oriented programming

Later look at Windows Forms applications GUI Based A little more complex

7

First C# Program

Let's do "Hello, World!" in C#

88

Start Visual Studio 2008

Your Start Page will look different.

99

Create a New Project

1010

Select Project Attributes

1111

Template for a Console Application

Generated automatically by Visual Studio

1212

The Hello World Program

1313

Build the Project

1414

Run the ProgramClick here to run

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The Hello World Program

1616

Possibly Unfamiliar Features

Overview(Details to Follow)

Namespace

using ... ;

class Program

static void Main (string[] args)

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Namespace Helps avoid name conflicts in large projects

Not necessary, or particularly helpful, on small projects

Visual Studio automatically wraps everything with

namespace projectName{

}

OK to delete if you wish.Or just ignore

Be careful when reusing source code.

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using System;

Recall the line:

Console.WriteLine("Hello, World!");

“Console” is a class in the System namespace

To refer to something outside the current namespace, you normally have to prefix the name with the namespace:

System.Console.WriteLine("Hello, World!");

“using System;” permits us to not do this.

C# programs typically begin with lots of “using” statements

19

"using" Statements

We could delete the other three "using" statements.

Included in the template by Visual Studio because they are frequently needed But not needed by this program.

20

using System If we delete "using System" we get a

compile time error. Compiler does not know about class Console.

21

Editor Shows Errors

Notice squiggly underlines.

22

using System If we prefix Console with the namespace

System, there is no error.namespace Hello

{

class Program

{

static void Main(string[] args)

{

System.Console.WriteLine("Hello, World!");

System.Console.ReadLine(); // Keep window open

}

}

}

"using System" saves typing and clutter.

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Things to Notice

In C# everything is in a class. Unlike C and C++

No significance in this simple console app. Very important in real programs.

Think of “class Program” as a wrapper required by the environment.

We will use C# classes later in the course. Similar to classes in C++ and Java.

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Things to Notice

Every C# program must have a “Main”

static void Main(string[ ] args)

Note capitalization. “static” means that the function is associated with the

class as a whole rather than with a specific object. Like C++. We never instantiate class Program.

“string[ ] args” permits arguments to be passed in from the command line as in standard C.

Not normally used for Windows applications. OK to ignore. (Just leave the parentheses empty)

static void Main()

2525

Things to Notice

Like standard C and C++

C# is case sensitive

System.Console.Writeline("Hello, World!"); gets a compile error

static void main()

doesn’t work

2626

Things to Notice

Like standard C++

the characters // say that the rest of the line is a comment.

Traditional C comments also work.

/* This is a traditional C comment */

27

Running Outside the IDE

We have an executable file: Hello.exe

27

28

Path to the Executable

28

29

Double Click the .exe File

29

30

Deploying the Program

Hello.exe is a complete executable program. Called an assembly (Microsoft terminology) MSIL

Microsoft Intermediate Language, not machine code “Managed code” Runs under the .NET Common Language Runtime

(CLR) Compiled into machine code as needed. (JIT Compiler)

Can be moved to another directory

Can be copied to another Windows system that has the .NET Framework installed

Can be run from the command line in a Windows console window 30

31

From a Console Window

31

Copy Hello.exe to C:

Open Command Prompt window and cd to C:

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Assignment

Before next class:

Read Chapter 1.

Do the examples from this class for yourself.