Chapter 1 Introduction to Programming and C# Programming in C#.NET © 2003 by The McGraw-Hill Companies, Inc. All rights reserved

Chapter 1Introduction to

Programming and C#

Programming in C# .NET

© 2003 by The McGraw-Hill Companies, Inc. All rights reserved.

© 2003 by The McGraw-Hill Companies, Inc. All rights reserved.1- 2

Objectives

• Describe the process of visual program design and development.

• Explain the term object-oriented programming.• Explain the concepts of classes, objects,

properties, methods, and events.• List and describe the three steps for writing a C#

program.• Describe the various files that make up a C#

project.


Objectives cont.

• Identify the elements in the Visual Studio environment.

• Define design time, run time, and break time.• Write, run, save, print, and modify your first C#

program.• Identify syntax errors, run-time errors, and logic

errors.• Look up C# topics in Help.


Writing Windows Applications with C#

• Projects look and act like standard Windows programs

• C# and Windows Forms tools will be used

• Graphical User Interface (GUI) includes– Forms– Controls– Object-oriented programming


Programming Languages

• Procedural– Specify exact sequence of all operations– Includes BASIC, C, COBOL, FORTRAN, PL/I

and Pascal

• Event Driven– Provided many elements of an object oriented

language– Includes early versions of Visual Basic


Programming Languages cont.

• Object Oriented– Programs are not procedural– User actions cause events to occur– Includes C# and Visual Basic. NET


The Object Model

• Objects – a thing or a noun• Properties – adjectives that describe objects• Methods – actions associated with objects• Events – occur when the user takes an

action or as the result of an action by another object

• Classes – a template used to create a new object


Object Model Analogy

• An individual car is an object• Make, model, color, engine, and number of

doors are properties of the car• Methods of the car might include Start,

SpeedUp, SlowDown, and Stop• Events of the car might include Arrive or

Crash• A car is an instance of the Automobile class


Microsoft’s Visual Studio.NET

• Includes C#, Visual Basic, Visual C++, and the .NET Framework

• The Framework allows objects from different languages to operate together

• All .NET languages compile to Microsoft Intermediate Language (MSIL)

• Managed code runs in the Common Language Runtime (CLR)


C#

• C# comes with Visual Studio .NET or can be purchased standalone

• Standalone versions– Standard Edition– Professional Edition– Enterprise Developer Edition– Enterprise Architect Edition


Writing C# Programs

• Three step process for planning and creating the project:– Setting up the user interface– Defining the properties– Creating the code


Planning

• Design the user interface– Draw a sketch of the screens– Consult with the user

• Plan the properties– Write down properties to be set or changed

• Plan the C# code– Plan classes and methods– Determine events to code– Write actions in pseudocode


Programming

• Define the user interface– Create required forms and controls (objects)

• Set the properties– Give each object a name– Define required attributes of each object

• Write the code– Write C# programming statements to carry out

actions


C# Application Files

• A solution consists of one or more projects

• Each project can have one or more form files

• Other files are created when you run your project


C# Application Files cont.

• .sln The solution file• .suo Solution user options file• .cs Holds definition of a form, its

controls, and code statements• .resx Resource file for a form• .csproj A project file• .csproj.user The project user option file


The Visual Studio Environment

• Visual Studio is an integrated development environment (IDE) used by all .NET languages

• The IDE consists of tools including– Form designer

– Editor

– Compiler

– Debugger

– Object browser

– Help facility


The Visual Studio Environment cont.

• The IDE Start Page• The New Project Dialog• The IDE Main Window• The Toolbars• The Document Window

• The Form Designer• The Solution Explorer

Window• The Properties Window• The Toolbox• Help


C# Modes

• Design time – Used to design the user interface and write code

• Run time – Used for testing and running a project

• Break time – Occurs when you get a run-time error or pause project execution


Writing Your First C# Project

For your first C# project, you will create a form with three controls. This simple project will display the message “Hello World” in a label when the user clicks the Push Me button and will terminate when the user clicks the Exit button.

• Set Up Your Workspace1. Run Visual Studio2. Start a New Project

– Do not create a new folder for your project

3. Set Up Your Environment– The “push pin” icon disables AutoHide

• Plan the Project


Writing Your First C# Project cont.

• Define the User Interface1. Set Up the Form

2. Place Controls on the Form– Right-click a control to display a context menu

– Lock Controls prevents accidental movement of the controls


Writing Your First C# Project cont.

• Set Properties1. Set the Name and Text Properties for the Label

• In System.Windows.Forms.Label, System.Windows.Forms is the namespace and Label is the actual class.

• The Text property determines what will be displayed on the form.

2. Set the Name and Text Properties for the First Button

3. Set the Name and Text Properties for the Second Button

4. Change the Properties of the Form


C# Events

• C# events are caused by user actions

• Write code called event-handling methods

• C# ignores events with no methods


C# Event-Handling Methods

• A method is a set of statements beginning with a function header

• Method statements are enclosed in braces {}• Event handlers are automatically named with format

– ObjectName_EventName

• Basic event-handling method syntaxprivate void ObjectName_EventName( . . . ){

Statements in the method}


C# Event-Handling Methods cont.

• private keyword indicates this method can only be executed by the current class (form)

• void keyword indicates this method does not return any value when executed


C# Code Statements

• Comment statement– Used for project documentation

– Programmers should include comments to clarify their projects

– Single-line comments begin with double slashes //Example: //Exit the project

– Multiline comments begin with /* and end with */Example: /* Programmer: Bradley/Millspaugh

Date: June 203 */


C# Code Statements cont.

• Terminate most C# statements with a semicolon (;)• Assignment statement

– Assigns a value to a property or variable

– Operate from left to right– General form Object.Property = value;

– Literals are enclosed in quotation marksExample: titleLabel.Text = “A Snazzy Program”;

– Numbers and True/False do not use quotation marks


C# Code Statements cont.

• Syntax to execute a method of an objectObject.Method();

• Methods always have parenthesis• Properties do not have parenthesis• Method to terminate execution

this.Close;

• this refers to the current object and can be omitted


Coding Event-Handling Methods for Hello World

• Double-click control to add code to event-handling method

• Indent all lines between the braces• Leave a blank line after comments at top of method• IntelliSense pops up list of properties and methods after

typing a period after object name• The smart editor displays messages at bottom of screen

in the Task List• Asterisk next to file name in tab to indicate there are

unsaved changes in the file


Run the Project

• Three ways to run the project– Open the Debug menu and choose Start– Press the Start button on the toolbar– Press F5, the shortcut key for the Start

command


Save Your Work

• Files are saved each time you build (compile) or execute (run) your project

• To manually save, open Visual Studio File menu and choose Save All

• To close the project, open the File menu and choose Close Solution


Open a Saved Project

• If project appears on the Start Page, click on its name

• Click on the Open Project button on the Start Page and browse for .sln file

• Select Open Solution from the Visual Studio File menu and browse for .sln file

• Choose the solution from the Files / Recent Projects menu item


Modify the Project

• The Font property is a Font object with a number of properties

• The TextAlign property determines the alignment of text in the control

• The Text property is used to display text on a button control


Print the Code

• The colors on the screen will appear on the printed output if you are using a color printer

• To print code:1. Display code in the Editor window

2. Select File / Print

3. Click OK


Finding and Fixing Errors

• Three types of programming errors:– Syntax errors– Run-time errors– Logic errors


Syntax Errors

• Occur if you break C#’s rules for punctuation, format, or spelling

• Smart editor finds most syntax errors• A compile error is an error found by the compiler• A squiggly line is placed under the part of code

line that the editor cannot interpret• Double-click on error in Task list to jump to error

line


Run-Time Errors

• Causes project to halt execution

• C# displays dialog box and highlights statement causing the error

• Statements that cannot execute correctly cause run-time errors


Logic Errors

• Program runs but produces incorrect results

• These errors are often overlooked

• Check all aspects of the project output– Computations– Text– Spacing


Project Debugging

• Debugging – Finding and fixing “bugs” in code

• Recompile program after debugging

• A clean compiles means you have zero syntax errors when you compile your program


Naming Rules

• Good programmers follow standards. You should have a set of standards and always follow them.

• C# naming rules– C# requires object name to begin with a letter or

an underscore– Name can contain letters, digits, and underscore– Name can not contain a space or punctuation

mark


Naming Conventions

• Camel casing – Begin name with a lowercase letter and capitalize each additional word in the name

• Append name of control to a meaningful name• Do not use abbreviations• Do not keep default names assigned by C#• Do not name objects with numbers• Pascal casing – Capitalize first letter of name and

all other words in name of forms and other classes


Visual Studio Help

• Visual Studio Help includes the Microsoft Developer Network library (MSDN) which provides:– Books– Technical articles– Microsoft Knowledge Base– Reference materials for the Visual Studio IDE,

the .NET Framework, C#, Visual Basic, and C++


Installing and Running MSDN

• You can run MSDN from– A hard drive– A network drive– A CD– The Web

• By default, MSDN is installed on the hard drive


Viewing Help Topics

• To view a Help topic:1. Choose Contents, Index, or Search2. Select a topic3. Page appears in the Document window

• Filter the Help topics with Filtered By• Press F1 for context-sensitive Help• Press Shift + F1 for context-sensitive Help

about the environment


Managing Windows

• To close a window that is part of a tabbed window, click the window’s Close button

• To hide a window that is part of a tabbed window, right-click the tab and select Hide

• To switch to another window that is part of a tabbed window, click on its tab


Summary

• C# is an object-oriented language used to write GUI applications.

• The OOP object model uses classes to create objects with properties, methods, and events.

• C# is part of Visual Studio .NET which has four editions.

• The languages of the .NET Framework compile to MSIL and run in the CLR.

• To plan a project, sketch the user interface, list the objects and properties needed, then plan event-handling methods.


Summary cont.

• The three steps to create a C# project are define user interface, set properties, and write code.

• A C# application is called a solution.• The Visual Studio IDE consists of several tools.• C# has three modes: design time, run time, and

break time.• The Visual Studio IDE can be customized.• Create the user interface by adding controls to a

form.


Summary cont.

• The Name property is used to refer to a control in code. The Text property holds words to be displayed on the screen.

• C# code is written in methods.• Project comments are used for documentation.• Most C# statements are terminated with semicolon.• Assignment statements assign a value to a property

or variable.• The this.Close method terminates program execution.


Summary cont.

• Respond to events by writing event handlers.• Print out C# code for documentation.• Three types of errors are syntax, run-time, and logic

errors.• Finding and fixing program errors is called

debugging.• You must have a clean compile to execute program.• Use good naming conventions.• C# Help contains descriptions of all project elements

and their uses.

Documents

Chapter 1 Introduction to Programming and C# Programming in C#.NET © 2003 by The McGraw-Hill Companies, Inc. All rights reserved