Introduction to Visual Studio and CSharpdotline-sistemas.com/livros/Introduction to Visual Studio...

UniversityCollegeofSoutheastNorway

http://home.hit.no/~hansha

IntroductiontoVisualStudioandC#

HANS-PETTERHALVORSEN,2016.09.26

2

TableofContents1. Introduction......................................................................................................................5

1.1. VisualStudio...............................................................................................................5

1.2. C#................................................................................................................................6

1.3. .NETFramework.........................................................................................................6

1.4. Object-OrientedProgramming(OOP)........................................................................7

2. VisualStudio......................................................................................................................8

2.1. Introduction................................................................................................................8

2.2. GettingStarted...........................................................................................................8

2.2.1. IntegratedDevelopmentEnvironment(IDE).......................................................8

2.2.2. NewProject.........................................................................................................9

2.2.3. SolutionExplorer...............................................................................................10

2.2.4. Toolbox..............................................................................................................11

2.2.5. EditorsandDesigners........................................................................................12

2.2.6. Propertieswindow............................................................................................12

2.2.7. BuildandDebugTools.......................................................................................13

3. WindowsProgramming...................................................................................................15

3.1. Introduction..............................................................................................................15

3.1.1. WindowsForms.................................................................................................15

3.1.2. WPF...................................................................................................................16

3.2. HelloWorld...............................................................................................................16

4. GettingStartedwithC#...................................................................................................19

3 TableofContents

Tutorial:IntroductiontoVisualStudioandC#

4.1. Introduction..............................................................................................................19

4.2. DataTypesandVariables..........................................................................................19

4.2.1. Booleantype.....................................................................................................20

4.2.2. Numerictypes:Integrals,FloatingPoint,Decimal............................................20

4.2.3. Stringtype.........................................................................................................20

4.2.4. Arrays................................................................................................................21

4.3. ControlFlow.............................................................................................................21

4.3.1. TheifStatement................................................................................................21

4.3.2. TheswitchStatement........................................................................................22

4.4. Loops.........................................................................................................................23

4.4.1. ThewhileLoop..................................................................................................23

4.4.2. ThedoLoop.......................................................................................................23

4.4.3. TheforLoop......................................................................................................24

4.4.4. TheforeachLoop...............................................................................................24

4.5. Methods...................................................................................................................24

4.5.1. NonstaticMethods............................................................................................25

4.5.2. StaticMethods..................................................................................................25

4.6. Namespaces..............................................................................................................26

4.7. Classes......................................................................................................................26

4.7.1. Constructor........................................................................................................27

4.8. Properties.................................................................................................................29

4.9. NamingConvention..................................................................................................31

5. MoreObject-orientedTechniques..................................................................................33

5.1. Inheritance................................................................................................................33

5.2. Polymorphism...........................................................................................................34

5.3. Encapsulation...........................................................................................................35

4 TableofContents


6. ExceptionHandling..........................................................................................................36

7. WindowsFormsExample................................................................................................38

8. WebProgramming..........................................................................................................44

8.1. Introduction..............................................................................................................44

8.2. HTML.........................................................................................................................44

8.3. WebBrowser............................................................................................................44

8.4. CSS............................................................................................................................45

8.5. JavaScript..................................................................................................................45

8.6. ASP.NET....................................................................................................................45

8.7. AJAX/ASP.NETAJAX.................................................................................................46

8.8. Silverlight..................................................................................................................46

9. DatabaseProgramming...................................................................................................47

9.1. ADO.NET...................................................................................................................47

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1. IntroductionInthisTutorialwewilluseVisualStudioandC#.C#istheprogramminglanguage,whileVisualStudioisthedevelopmentenvironment.

Usefullinks:

VisualStudio:http://msdn.microsoft.com/en-us/library/dd831853.aspx

C#:http://msdn.microsoft.com/en-us/library/kx37x362.aspx

1.1. VisualStudioMicrosoftVisualStudioisanintegrateddevelopmentenvironment(IDE)fromMicrosoft.ItcanbeusedtodevelopconsoleandgraphicaluserinterfaceapplicationsalongwithWindowsFormsapplications,websites,webapplications,andwebservicesinbothnativecodetogetherwithmanagedcodeforallplatformssupportedbyMicrosoftWindows,WindowsPhone,WindowsCE,.NETFramework,.NETCompactFrameworkandMicrosoftSilverlight.

Belowweseetheintegrateddevelopmentenvironment(IDE)inVisualStudio:

6 Introduction


Newprojectsarecreatedfromthe“NewProject”window:

1.2. C#C#ispronounced“seesharp”.C#isanobject-orientedprogramminglanguageandpartofthe.NETfamilyfromMicrosoft.C#isverysimilartoC++andJava.C#isdevelopedbyMicrosoftandworksonlyontheWindowsplatform.

1.3. .NETFrameworkThe.NETFramework(pronounced“dotnet”)isasoftwareframeworkthatrunsprimarilyonMicrosoftWindows.Itincludesalargelibraryandsupportsseveralprogramminglanguageswhichallowlanguageinteroperability(eachlanguagecanusecodewritteninotherlanguages).The.NETlibraryisavailabletoalltheprogramminglanguagesthat.NETsupports.Programswrittenforthe.NETFrameworkexecuteinasoftwareenvironment,knownastheCommonLanguageRuntime(CLR),anapplicationvirtualmachinethatprovidesimportantservicessuchassecurity,memorymanagement,andexceptionhandling.TheclasslibraryandtheCLRtogetherconstitutethe.NETFramework.

7 Introduction


1.4. Object-OrientedProgramming(OOP)Object-orientedprogramming(OOP)isaprogramminglanguagemodelorganizedaround"objects"ratherthan"actions"anddataratherthanlogic.Historically,aprogramhasbeenviewedasalogicalprocedurethattakesinputdata,processesit,andproducesoutputdata.

ThefirststepinOOPistoidentifyalltheobjectsyouwanttomanipulateandhowtheyrelatetoeachother,anexerciseoftenknownasdatamodeling.Onceyou'veidentifiedanobject,yougeneralizeitasaclassofobjectsanddefinethekindofdataitcontainsandanylogicsequencesthatcanmanipulateit.Eachdistinctlogicsequenceisknownasamethod.Arealinstanceofaclassiscalledan“object”oran“instanceofaclass”.Theobjectorclassinstanceiswhatyouruninthecomputer.Itsmethodsprovidecomputerinstructionsandtheclassobjectcharacteristicsproviderelevantdata.Youcommunicatewithobjects-andtheycommunicatewitheachother.

ImportantfeatureswithOOPare:

• ClassesandObjects• Inheritance• Polymorphism• Encapsulation

Simulawasthefirstobject-orientedprogramminglanguage.Simulawasdevelopedinthe1960sbyKristenNygaardfromNorway.

Java,Python,C++,VisualBasic.NETandC#arepopularOOPlanguagestoday.

SinceSimula-typeobjectsarereimplementedinC++,JavaandC#theinfluenceofSimulaisoftenunderstated.ThecreatorofC++(1979),BjarneStroustrup(fromDenmark),hasacknowledgedthatSimulawasthegreatestinfluenceonhimtodevelopC++.

8

2. VisualStudio

2.1. IntroductionHomepageofVisualStudio:http://www.microsoft.com/visualstudio

ThereexistdifferentversionsofVisualStudio,suchasVisualStudioExpress(free),VisualStudioProfessional,VisualStudioPremiumandVisualStudioUltimate.

2.2. GettingStarted

2.2.1. IntegratedDevelopmentEnvironment(IDE)

TheVisualStudioproductfamilysharesasingleintegrateddevelopmentenvironment(IDE)thatiscomposedofseveralelements:theMenubar,Standardtoolbar,varioustoolwindowsdockedorauto-hiddenontheleft,bottom,andrightsides,aswellastheeditorspace.Thetoolwindows,menus,andtoolbarsavailabledependonthetypeofprojectorfileyouareworkingin.

BelowweseetheVisualStudioIDE(IntegratedDevelopmentEnvironment):

9 VisualStudio


2.2.2. NewProject

Thefirstthingyoudowhenyouwanttocreateanewapplicationistocreateanewproject.

ThiscanbedonefromtheStartPage:

OrfromtheFilemenu:

Thenthe“NewProject”windowappears:

10 VisualStudio


Inthiswindowyouwillselectanappropriatetemplatebasedonwhatkindofapplicationyouwanttocreate,andanameandlocationforyourprojectandsolution.

Themostcommonapplicationsare:

• WindowsFormApplication• ConsoleApplication• WPFApplication• ASP.NETWebApplication• SilverlightApplication

2.2.3. SolutionExplorer

Solutionsandprojectscontainitemsthatrepresentthereferences,dataconnections,folders,andfilesthatyouneedtocreateyourapplication.Asolutioncontainercancontainmultipleprojectsandaprojectcontainertypicallycontainsmultipleitems.

11 VisualStudio


2.2.4. Toolbox

TheToolboxcontainsallthenecessarycontrols,etc.youneedtocreateyouruserinterface.SeeFigurebelow.

TheToolboxcontainsallthecontrols,etc.wecanuseinouruserinterface.

Inordertousetheminouruserinterface,wejustdraganddropthemtothe“Form”,asshownbelow:

12 VisualStudio


2.2.5. EditorsandDesigners

VisualStudiohasdifferenteditorsanddesigntools.

GraphicalUserInterfaceDesigner:

CodeEditor:

2.2.6. Propertieswindow

EachcontrolwehaveonouruserinterfacehaslotsofPropertieswecanset.

13 VisualStudio


ThisisdoneinthePropertieswindow:

2.2.7. BuildandDebugTools

InVisualStudiowehavelotsofBuildandDebuggingTools.

Buildmenu:

BelowweseetheBuildmenu:

Themostusedtoolis“BuildSolution”(ShortcutKey:F6).

Debugmenu:

BelowweseetheDebugmenu:

14 VisualStudio


Themostusedtoolis“StartDebugging”(ShortcutKey:F5).

15

3. WindowsProgramming

3.1. IntroductionWhencreatingordinaryWindowsapplications,wecanselectbetweenthefollowing:

• WindowsFormsApplication• WPFApplications(WindowsPresentationFoundation)

WindowsFormsisthestandardwayofcreatingWindowsapplicationsandhasexistedinmanyyears,evenbefore.NET1.0(2002)wasintroduced.WPFisanewapproachfromcreatingWindowsapplicationsandwasintroducedwith.NETFramework3.0(2006).

ForexamplehastheVisualStudioIDEbeenentirelyrewrittenusingWPF.

WindowsFormsApplicationandWPFApplicationswillbeexplainedinmoredetailbelow.

3.1.1. WindowsForms

WindowsFormsisthestandardwayofcreatingWindowsapplications.

Select“WindowsFormsApplication”inthe“NewProject”window:

16 WindowsProgramming


3.1.2. WPF

DevelopedbyMicrosoft,theWindowsPresentationFoundation(orWPF)isacomputer-softwaregraphicalsubsystemforrenderinguserinterfacesinWindows-basedapplications.

WPFisintendedtotakeoverforthetraditionalWindowsForms.

ThegraphicaluserinterfaceinWPFisdesignedusingXAML(ExtensibleApplicationMarkupLanguage).

XAML:

Followingthesuccessofmarkuplanguagesforwebdevelopment,WPFintroducesanewlanguageknownaseXtensibleApplicationMarkupLanguage(XAML),whichisbasedonXML.XAMLisdesignedasamoreefficientmethodofdevelopingapplicationuserinterfaces

Select“WPFApplication”inthe“NewProject”window:

3.2. HelloWorldWestartbycreatingatraditional“HelloWorld”applicationusingWindowsForms.Theapplicationisshownbelow:



TheVisualStudioIDElookslikethis:

InthisprojectweuseasimpleTextBox(textBox1)andwhenwestarttheprogramthetext“HelloWorld”iswrittentotheTextBox.

Thecodeisasfollows:

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace WindowsFormsApplication1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); }



private void Form1_Load(object sender, EventArgs e) { textBox1.Text = "Hello World"; } } }

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4. GettingStartedwithC#C#isamodernObject-orientedprogramminglanguage.

Object-orientedprogramming(OOP)isaprogrammingparadigmusing"objects"–datastructuresconsistingofdatafieldsandmethodstogetherwiththeirinteractions–todesignapplicationsandcomputerprograms.Programmingtechniquesmayincludefeaturessuchasdataabstraction,encapsulation,messaging,modularity,polymorphism,andinheritance.

4.1. IntroductionInthischapterwewillstartwiththebasicallprogramminglanguageshave:…

• DataTypesandVariables• ControlFlow:If-Else,etc.• Loops:WhileLoops,ForLoops,etc.

Furtherwewillintroducethefollowing:

• Namespaces• Classes• DataFields• Methods• Properties

InthenextchapterwewillgomoreindepthofwhatObject-orientedprogrammingisandintroducethefollowingimportantOOPtopics:

• Inheritance• Polymorphism• Encapsulation

Note!C#iscase-sensitive.

4.2. DataTypesandVariables

20 GettingStartedwithC#


“Variables”aresimplystoragelocationsfordata.YoucanplacedataintothemandretrievetheircontentsaspartofaC#expression.Theinterpretationofthedatainavariableiscontrolledthrough“Types”.

TheC#simpletypesconsistof:

• Booleantype• Numerictypes:Integrals,FloatingPoint,Decimal• Stringtype

4.2.1. Booleantype

Booleantypesaredeclaredusingthekeyword“bool”.Theyhavetwovalues:“true”or“false”.Inotherlanguages,suchasCandC++,booleanconditionscanbesatisfiedwhere0meansfalseandanythingelsemeanstrue.However,inC#theonlyvaluesthatsatisfyabooleanconditionistrueandfalse,whichareofficialkeywords.

Example:

bool content = true; bool noContent = false;

4.2.2. Numerictypes:Integrals,FloatingPoint,Decimal

Example:

int i=35; long y=654654;

float x; double y; decimal z;

4.2.3. Stringtype

Example:

string myString=”Hei på deg”;

Specialcharactersthatmaybeusedinstrings:



4.2.4. Arrays

Example:

int[] myInts = { 5, 10, 15 };

4.3. ControlFlowTobeabletocontroltheflowinyourprogramisimportantineveryprogramminglanguage.

Thetwomostimportanttechniquesare:

• TheifStatement• TheswitchStatement

4.3.1. TheifStatement

Theifstatementisprobablythemostusedmechanismtocontroltheflowinyourapplication.

Anifstatementallowsyoutotakedifferentpathsoflogic,dependingonagivencondition.Whentheconditionevaluatestoabooleantrue,ablockofcodeforthattrueconditionwillexecute.Youhavetheoptionofasingleifstatement,multipleelseifstatements,andanoptionalelsestatement.

Example:

bool myTest;



myTest=false; if (myTest==false)

MessageBox.Show("Hello");

Ifwehavemorethanonelineofcodethatthatshallbeexecuted,weneedtousebraces,e.g.:

bool myTest; myTest=false; if (myTest == false) {

MessageBox.Show("Hello1"); MessageBox.Show("Hello2");

}

Formorecomplexlogicweusetheif…elsestatement.

Example:

bool myTest; myTest=true; if (myTest == false) {

MessageBox.Show("Hello1"); } else {

MessageBox.Show("Hello2"); }

Oryoucanusenestedif…elseifsentences.

Example:

int myTest; myTest=2; if (myTest == 1) {

MessageBox.Show("Hello1"); } else if (myTest == 2) {

MessageBox.Show("Hello2"); } else {

MessageBox.Show("Hello3"); }

4.3.2. TheswitchStatement

Anotherformofselectionstatementistheswitchstatement,whichexecutesasetoflogicdependingonthevalueofagivenparameter.Thetypesofthevaluesaswitchstatementoperatesoncanbebooleans,enums,integraltypes,andstrings.



Example:

switch (myTest) {

case 1: MessageBox.Show("Hello1"); break;

case 2: MessageBox.Show("Hello2");

break;

default: MessageBox.Show("Hello3"); break; }

4.4. LoopsInC#wehavedifferentkindofloops:

• Thewhileloop• Thedoloop• Theforloop• Theforeachloop

4.4.1. ThewhileLoop

Awhileloopwillcheckaconditionandthencontinuestoexecuteablockofcodeaslongastheconditionevaluatestoabooleanvalueoftrue.

Example:

int myInt = 0; while (myInt < 10) {

MessageBox.Show("Inside Loop: " + myInt.ToString()); myInt++; } MessageBox.Show("Outside Loop: " + myInt.ToString());

4.4.2. ThedoLoop

Adoloopissimilartothewhileloop,exceptthatitchecksitsconditionattheendoftheloop.Thismeansthatthedoloopisguaranteedtoexecuteatleastonetime.Ontheotherhand,awhileloopevaluatesitsbooleanexpressionatthebeginningandthereisgenerallynoguaranteethatthestatementsinsidetheloopwillbeexecuted,unlessyouprogramthecodetoexplicitlydoso.

Example:



int myInt = 0; do {

MessageBox.Show("Inside Loop: " + myInt.ToString()); myInt++;

} while (myInt < 10); MessageBox.Show("Outside Loop: " + myInt.ToString());

4.4.3. TheforLoop

Aforloopworkslikeawhileloop,exceptthatthesyntaxoftheforloopincludesinitializationandconditionmodification.forloopsareappropriatewhenyouknowexactlyhowmanytimesyouwanttoperformthestatementswithintheloop.

Example:

for (int i = 0; i < 10; i++) {

MessageBox.Show("Inside Loop: " + myInt.ToString()); myInt++; } MessageBox.Show("Outside Loop: " + myInt.ToString());

4.4.4. TheforeachLoop

Aforeachloopisusedtoiteratethroughtheitemsinalist.Itoperatesonarraysorcollections.

Example:

string[] names = { "Elvis", "Beatles", "Eagles", "Rolling Stones" }; foreach (string person in names) {

MessageBox.Show(person); }

4.5. MethodsMethodsareextremelyusefulbecausetheyallowyoutoseparateyourlogicintodifferentunits.Youcanpassinformationtomethods,haveitperformoneormorestatements,andretrieveareturnvalue.Thecapabilitytopassparametersandreturnvaluesisoptionalanddependsonwhatyouwantthemethodtodo.

Methodsaresimilartofunctions,procedureorsubroutineusedinotherprogramminglanguages.Thedifferenceisthatamethodisalwaysapartofaclass.

Example:

public void ShowCarColor(string color)



{

MessageBox.Show("My Car is: " + color); }

WelearnmoreaboutmethodsintheClassessectionbelow.

Wehave2kindsofMethods:

• StaticMethods• NonstaticMethods(InstanceMethod)

StaticMethodsbelongstothewholeclass,whilenonstaticMethodsbelongtoeachinstancecreatedfromtheclass.

4.5.1. NonstaticMethods

Example:

Wedefinetheclass:

class Car {

//Nonstatic/Instance Method public void SetColor(string color) { MessageBox.Show("My Car is: " + color); } }

Thenweuseit:

Car myCar = new Car(); //We create an Instance of the Class myCar.SetColor("blue"); //We call the Method

4.5.2. StaticMethods

Example:

Wedefinetheclass:

class Boat { //Static Method public static void SetColor(string color) { MessageBox.Show("My Boat is: " + color); } }



Thenweuseit:

Boat.SetColor("green");

i.e.,wedon’tneedtocreateanobject/instantiatingtheclassbeforeweusetheStaticMethod.

4.6. NamespacesNamespacesareC#programelementsdesignedtohelpyouorganizeyourprograms.Theyalsoprovideassistanceinavoidingnameclashesbetweentwosetsofcode.ImplementingNamespacesinyourowncodeisagoodhabitbecauseitislikelytosaveyoufromproblemslaterwhenyouwanttoreusesomeofyourcode.

YouspecifytheNamespacesyouwanttouseinthetopofyourcode.

Example:

WhenyoucreateanewWindowsFormsapplication,thefollowingdefaultnamespaceswillbeincluded.

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; …

Itisjusttoaddmorewhenyouneedit.

MoreaboutNamespaceslater.

4.7. ClassesThefirststepinOOPistoidentifyalltheobjectsyouwanttomanipulateandhowtheyrelatetoeachother,anexerciseoftenknownasdatamodeling.Onceyou'veidentifiedanobject,yougeneralizeitasaclassofobjectsanddefinethekindofdataitcontainsandanylogicsequencesthatcanmanipulateit.Eachdistinctlogicsequenceisknownasamethod.Arealinstanceofaclassiscalledan“object”oran“instanceofaclass”.Theobjectorclassinstanceiswhatyouruninthecomputer.Itsmethodsprovidecomputerinstructionsandtheclassobjectcharacteristicsproviderelevantdata.Youcommunicatewithobjects-andtheycommunicatewitheachother.



EverythinginC#isbasedonClasses.Classesaredeclaredbyusingthekeywordclassfollowedbytheclassnameandasetofclassmemberssurroundedbycurlybraces.

AclassnormallyconsistsofMethods,FieldsandProperties.

Everyclasshasaconstructor,whichiscalledautomaticallyanytimeaninstanceofaclassiscreated.Thepurposeofconstructorsistoinitializeclassmemberswhenaninstanceoftheclassiscreated.Constructorsdonothavereturnvaluesandalwayshavethesamenameastheclass.

Example:

Wedefinethefollowingclass:

class Car {

public string color; //Field

//Method public void ShowCarColor() {

MessageBox.Show("My Car is: " + color);

}

}

Thenwecanuseit:

Car myCar = new Car(); //We create an Instance of the Class myCar.color = "blue"; //We set a value for the color Field myCar.ShowCarColor(); //We call the Method

Theresultisasfollows:

4.7.1. Constructor

Thepurposeofconstructorsistoinitializeclassmemberswhenaninstanceoftheclassiscreated.

Example:

WecanuseaConstructortocreatea“default”colorforourcar.

Wedefinetheclass:



class Car { public string color; //Field //Constructor - Used to initialize the Class public Car() { color="green"; } //Method public void ShowCarColor() { MessageBox.Show("My Car is: " + color); } }

Thenwecanuseit:

Car myCar = new Car(); //We create an Instance of the Class myCar.ShowCarColor(); //We call the Method myCar.color = "blue"; //We set a value for the color Field myCar.ShowCarColor(); //We call the Method

Theresultsareasfollows:

…

Example:

Wecanalsodothefollowing:

class Car { public string color; //Field //Constructor - Used to initialize the Class public Car(string initColor) { color = initColor;



} //Method public void ShowCarColor() { MessageBox.Show("My Car is: " + color); } }

Thenweuseit:

Car myCar = new Car("green"); //We create an Instance of the Class myCar.ShowCarColor(); //We call the Method

Newfeature:InitializationanobjectwithoutaConstructor:

InC#4.0wecandothefollowing:

WedefinetheClass(withoutanycontructor):

class Car { public string color; //Field public string model; //Field //Method public void ShowCarColor() { MessageBox.Show("My Car Color is: " + color); MessageBox.Show("My Car Model is: " + model); } }

Thenwedothefollowing:

Car myCar = new Car {color="white", model="2004"}; myCar.ShowCarColor(); //We call the Method

4.8. PropertiesPropertiesprovidetheopportunitytoprotectafieldinaclassbyreadingandwritingtoitthroughtheproperty.Inotherlanguages,thisisoftenaccomplishedbyprogramsimplementingspecializedgetterandsettermethods.C#propertiesenablethistypeofprotectionwhilealsolettingyouaccessthepropertyjustlikeitwasafield.

Example:

WedefineaClasswithPropertiesandaMethod:

class Car {



public string Name {get; set;} public string Color {get; set;} public void ShowCarProperties() { MessageBox.Show("My Car Name is: " + Name); MessageBox.Show("My Car Color is: " + Color); } }

Thenwecanuseit:

Car myCar = new Car(); myCar.Name="Volvo"; myCar.Color="Blue"; myCar.ShowCarProperties();

Theresultsare:

…

Sofar,theonlyclassmembersyou'veseenareFields,Properties,Methods,andConstructors.Hereisacompletelistofthetypesofmembersyoucanhaveinyourclasses:

• Constructors• Destructors(oppositeofConstructors)• Fields• Methods• Properties• Indexers• Delegates• Events• NestedClasses



4.9. NamingConventionThereisdifferentnameconventionforhowtospecifyyourvariables,classesandMethods,etc.

Camelnotation:

Forvariablesandparameters/argumentswenormallyuse“Camelnotation”.

Examples:

string myCar; int number; string backColor;

→InCamelcasingthefirstletterofanidentifierislowercaseandthefirstletterofeachsubsequentconcatenatedwordiscapitalized.

Pascalnotation:

Forclasses,methodsandproperties,wenormallyuse“Pascalnotation”.

Examples:

class Car { void ShowCarColor() { … } }

→InPascalcasingthefirstletterintheidentifierandthefirstletterofeachsubsequentconcatenatedwordarecapitalized.

ForNamespacesweusePascalcasingandadotseparator.

Examples:

System.Drawing System.Collections.Generics

Controls:

Forcontrolsonyouruserinterfaceweeitheruse“Pascalnotation”or“Hungariannotation”,butsticktooneofthem!

Examples:

“Pascalnotation”:

LoginName LoginPassword



“Hungariannotation”:

txtName txtPassword lblName btnCancel

Where“txt”meansitisaTextControl,“lbl”aLabelControl,“btn”aButtonControl,etc.

Acronyms:

Casingofacronymsdependsonthelengthoftheacronym.Allacronymsareatleasttwocharacterslong.Ifanacronymisexactlytwocharacters,itisconsideredashortacronym.Anacronymofthreeormorecharactersisalongacronym.

Ingeneral,youshouldnotuseabbreviationsoracronyms.Thesemakeyournameslessreadable.Similarly,itisdifficulttoknowwhenitissafetoassumethatanacronymiswidelyrecognized.

Butifyoumust,therulesareasfollows:

ShortacronymExamples(twocharacters):

DBRate

ApropertynamedDBRateisanexampleofashortacronym(DB)usedasthefirstwordofaPascal-casedidentifier.

ioChannel

AparameternamedioChannelisanexampleofashortacronym(IO)usedasthefirstwordofacamel-casedidentifier.

LongacronymExamples(threeormorecharacters):

XmlWriter

AclassnamedXmlWriterisanexampleofalongacronymusedasthefirstwordofaPascal-casedidentifier.

htmlReader

AparameternamedhtmlReaderisanexampleofalongacronymusedasthefirstwordofacamel-casedidentifier.

33

5. MoreObject-orientedTechniques

InthischapterwewillintroducethefollowingObject-orientedtechniques:

• Inheritance• Polymorphism• Encapsulation

5.1. InheritanceInheritanceisoneoftheprimaryconceptsofobject-orientedprogramming.Itallowsyoutoreuseexistingcode.Througheffectiveemploymentofreuse,youcansavetimeinyourprogramming.

Example:

WedefinetheBaseclass:

class Car { public void SetColor(string color) { MessageBox.Show("My Car is: " + color); } }

ThenwedefineanewclassthatinheritsfromtheBaseClass:

class Volvo : Car { //In this simple Example this class does nothing! }

Thenwestartusingtheclasses:

Car myCar = new Car(); myCar.SetColor("blue"); Volvo myVolvo = new Volvo();

34 MoreObject-orientedTechniques


myVolvo.SetColor("green");

Asyoucanseewecanusethe“SetColor()”MethodthathasbeendefinedintheBaseClass.

5.2. PolymorphismAnotherprimaryconceptofobject-orientedprogrammingisPolymorphism.Itallowsyoutoinvokederivedclassmethodsthroughabaseclassreferenceduringrun-time.

Example:

WestartwithaBaseClass:

class Car { public virtual void CarType() { MessageBox.Show("I am a Car"); } }

Thevirtualmodifierindicatestoderivedclassesthattheycanoverridethismethod.

Thenwecreate3newClassesthatderivefromtheBaseClass:

class Volvo : Car { public override void CarType() { MessageBox.Show("I am a Volvo"); } } class Ford : Car { public override void CarType() { MessageBox.Show("I am a Ford"); } } class Toyota : Car { public override void CarType() { MessageBox.Show("I am a Toyota"); } }

These3classesinherittheCarclass.EachclasshasaCarType()methodandeachCarType()methodhasanoverridemodifier.Theoverridemodifierallowsamethodtooverridethevirtualmethodofitsbaseclassatrun-time.

Thenwecanuseit:

Car[] car = new Car[4]; car[0] = new Car();

35 MoreObject-orientedTechniques


car[1] = new Volvo(); car[2] = new Ford(); car[3] = new Toyota(); foreach (Car carmodel in car) { carmodel.CarType(); }

Theresultis:

… … …

→ThisisPolymorphism.

5.3. EncapsulationEncapsulationmeansthattheinternalrepresentationofanobjectisgenerallyhiddenfromviewoutsideoftheobject'sdefinition.Typically,onlytheobject'sownmethodscandirectlyinspectormanipulateitsfields.

WecansetdifferentAccessrightsonClassesandMethods:

36

6. ExceptionHandlingInprogrammingerrorandexceptionhandlingisveryimportant.C#hasbuilt-inandreadytousemechanismtohandlethis.Thismechanismisbasedonthekeywordstry,catch,throwandfinally.

Exceptionsareunforeseenerrorsthathappeninyourprograms.Mostofthetime,youcan,andshould,detectandhandleprogramerrorsinyourcode.Forexample,validatinguserinput,checkingfornullobjects,andverifyingthevaluesreturnedfrommethodsarewhatyouexpect,areallexamplesofgoodstandarderrorhandlingthatyoushouldbedoingallthetime.

However,therearetimeswhenyoudon'tknowifanerrorwilloccur.Forexample,youcan'tpredictwhenyou'llreceiveafileI/Oerror,runoutofsystemmemory,orencounteradatabaseerror.Thesethingsaregenerallyunlikely,buttheycouldstillhappenandyouwanttobeabletodealwiththemwhentheydooccur.Thisiswhereexceptionhandlingcomesin.

Whenexceptionsoccur,theyaresaidtobe“thrown”.C#usesthekeywordstry,catch,throwandfinally.Itworkslikethis:Amethodwilltrytoexecuteapieceofcode.Ifthecodedetectsaproblem,itwillthrowanerrorindication,whichyourcodecancatch,andnomatterwhathappens,itfinallyexecutesaspecialcodeblockattheend.

Thesyntaxisasfollows:

MyMethod() { try

{ ... //Do Something that can cause an Exception }

catch { ... //Handle Exceptions }

finally { ... //Clean Up }

}

Example:

public void WriteDaqData(double analogDataOut) { Task analogOutTask = new Task();

37 ExceptionHandling


AOChannel myAOChannel; try { myAOChannel = analogOutTask.AOChannels.CreateVoltageChannel( aoChannel, "myAOChannel", 0, 5, AOVoltageUnits.Volts ); AnalogSingleChannelWriter writer = new AnalogSingleChannelWriter(analogOutTask.Stream); writer.WriteSingleSample(true, analogDataOut); } catch (Exception e) { string errorMessage; errorMessage = e.Message.ToString(); } finally { analogOutTask.Stop(); } }

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7. WindowsFormsExample

Inthischapterwewillgothroughalargeexample.InthisexamplewewillcreateanapplicationinVisualStudiothatcontrolsthefollowingwatertankprocess:

Thepurposeistocontrolthelevelinthewatertank.Inordertocommunicatewiththephysicalprocess,weuseaNIUSB-6008DAQdevice:

Wewillnotshowallthedetailsinthecode,butfocusonthestructure.

BelowweseetheuserinterfacewehavecreatedinVisualStudio:

39 WindowsFormsExample


BelowweseetheVisualStudioproject:

Westartwithdefiningtheclassesweneedinourapplication.

IntheSolutionExplorerwehavedefineda“Classes”folderwhereweputalltheclasseswecreate:



Inordertocreatenewclassesweright-clickintheSolutionExplorerandselect“Add-NewItem…”:

NextweselecttheClassiteminthe“AddNewItem”window:



Classes:

Westartwiththe“Daq”ClassthatcontainslogicforreadingandwritingtotheDAQdevice:

//Include necessary Namespaces using System; using System.Collections.Generic; using System.Linq; using System.Text; using NationalInstruments; using NationalInstruments.DAQmx; namespace Tuc.Control //We define a useful namespace { public class DaqData { public string aiChannel; public string aoChannel; //Constructor public DaqData(...) { ... }

//Method public double ReadDaqData() {

... }

//Method

public void WriteDaqData(...) { ... } } }



Itisgoodpracticetocreateanewfileforeachnewclasswedefine.ThenwestartbydefiningameaningfulNamespace.NextwedefineourClasswithnecessaryFields,PropertiesandMethods.

WealsoneedtoincludethenecessaryNamespaceourClasswillneed.Inthisexamplewehaveincludedsome3.partyAssembliesfromNationalInstruments:

using NationalInstruments; using NationalInstruments.DAQmx;

TheseAssembliescontainsthedrivertotheNIUSB-6008DAQdeviceweareusing.

TheAssembliesweusemustbeaddedinthe“References”folderintheSolutionExplorer:

MainApplication:

InourmainapplicationwestartwithincludingourNamespace:

using NationalInstruments; using NationalInstruments.UI; using NationalInstruments.UI.WindowsForms; using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using Tuc.Control; namespace Control_Application { public partial class Form1 : Form {

... } }



Itisalsoagoodideatocreatedifferentregionsinordertostructureyourcodebetter.Thiscanbedonelikethis:

//Comment # region

... //Your Code # endregion

InthiswayourMainApplicationmaylooklikethis:

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8. WebProgramming

8.1. IntroductionTodaymostoftheapplicationsfocusontheInternet,wheretheapplicationscanbeviewedinastandardWebBrowser.StaticWebpagesarebasedonHTMLandCSS.Inordertocreatemoreadvancedapplications,weneedmorepowerfultools.

Importantframeworksandtoolsforcreatingdynamicwebpages:

• ASP.NET• AJAX/ASP.NETAJAX• JavaScript• Silverlight

Theseframeworksandtoolswillbeexplainedbelow.

SeetheTutorial“ASP.NETandWebProgramming”formoredetails.

8.2. HTMLHTML,whichstandsforHyperTextMarkupLanguage,isthepredominantmarkuplanguageforwebpages.HTMListhebasicbuilding-blocksofwebpages.

HTMLiswrittenintheformofHTMLelementsconsistingoftags,enclosedinanglebrackets(like<html>),withinthewebpagecontent.HTMLtagsnormallycomeinpairslike<h1>and</h1>.Thefirsttaginapairisthestarttag,thesecondtagistheendtag(theyarealsocalledopeningtagsandclosingtags).Inbetweenthesetagswebdesignerscanaddtext,tables,images,etc.

8.3. WebBrowserThepurposeofawebbrowseristoreadHTMLdocumentsandcomposethemintovisualoraudiblewebpages.ThebrowserdoesnotdisplaytheHTMLtags,butusesthetagstointerpretthecontentofthepage.

45 WebProgramming


TodaywehavethefollowingmajorWebBrowsers:

• InternetExplorer(byMicrosoft)• Firefox(byMozilla)• Chrome(byGoogle)• Safari(byApple)• Opera(byOperafromNorway)

8.4. CSSWebbrowserscanalsorefertoCascadingStyleSheets(CSS)todefinetheappearanceandlayoutoftextandothermaterial.

TheW3C,maintainerofboththeHTMLandtheCSSstandards

8.5. JavaScriptJavaScriptisanobject-orientedscriptinglanguagebasicallyusedtocreatedynamicwebpages.JavaScriptisprimarilyusedintheformofclient-sideJavaScript,implementedaspartofawebbrowserinordertoprovideenhanceduserinterfacesanddynamicwebsites.

8.6. ASP.NETASP.NETisawebapplicationframeworkdevelopedbyMicrosofttoallowprogrammerstobuilddynamicwebsites,webapplicationsandwebservices.

ASP.NETispartoftheVisualStudiopackage

ItwasfirstreleasedinJanuary2002withversion1.0ofthe.NETFramework,andisthesuccessortoMicrosoft'sActiveServerPages(ASP)technology.ASP.NETisbuiltontheCommonLanguageRuntime(CLR),allowingprogrammerstowriteASP.NETcodeusinganysupported.NETlanguage,suchasC#andVB.NET.

ASP.NETwebpagesorwebpage,knownofficiallyasWebForms],arethemainbuildingblockforapplicationdevelopment.Webformsarecontainedinfileswithan“.aspx”extension.

Select“ASP.NETApplication”inthe“NewProject”window:

46 WebProgramming


8.7. AJAX/ASP.NETAJAXAJAXisanacronymforAsynchronousJavaScriptandXML.AJAXisagroupofinterrelatedwebdevelopmentmethodsusedontheclient-sidetocreateinteractivewebapplications.WithAjax,webapplicationscansenddatato,andretrievedatafrom,aserverasynchronously(inthebackground)withoutinterferingwiththedisplayandbehavioroftheexistingpage.

ASP.NETAJAXisasetofextensionstoASP.NETdevelopedbyMicrosoftforimplementingAJAXfunctionality.

8.8. SilverlightMicrosoftSilverlightisanapplicationframeworkforwritingandrunningbrowserplug-insorotherrichinternetapplications,withfeaturesandpurposessimilartothoseofAdobeFlash.Therun-timeenvironmentforSilverlightisavailableasaplug-informostwebbrowsers.SilverlightisalsooneofthetwoapplicationdevelopmentplatformsforWindowsPhone7/8.

ThelatestversionisSilverlight5.0.

SilverlightisbasedonWPF,soinSilverlightapplications,userinterfacesaredeclaredinExtensibleApplicationMarkupLanguage(XAML)andprogrammedusingasubsetofthe.NETFramework.

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9. DatabaseProgrammingMostoftoday’sapplicationsuseabackenddatabasetostoreimportantdata,e.g.,Facebook,Twitter,etc.

InordertousedatabasesinourapplicationsweneedtoknowStructuredQuerylanguage(SQL).FormoreinformationaboutSQL,seethefollowingTutorial:

StructuredQueryLanguage(SQL)

Inadditionyouneedtoknowaboutdatabasesystems.Wehavedifferentkindofdatabasesystemsandlotsofdifferentvendors.SincethisTutorialisaboutVisualStudioandC#,wewilluseMicrosoftSQLServer.FormoreinformationaboutdatabasesystemsingeneralandspeciallySQLServer,seethefollowingTutorial:

IntroductiontoDatabaseSystems

TheTutorialsareavailablefrom:http://home.hit.no/~hansha

9.1. ADO.NETADO.NET(ActiveXDataObjectfor.NET)isasetofcomputersoftwarecomponentsthatprogrammerscanusetoaccessdataanddataservices.ItisapartofthebaseclasslibrarythatisincludedwiththeMicrosoft.NETFramework.Itiscommonlyusedbyprogrammerstoaccessandmodifydatastoredinrelationaldatabasesystems,thoughitcanalsoaccessdatainnon-relationalsources.

Hans-PetterHalvorsen,M.Sc.

E-mail:[email protected]

Blog:http://home.hit.no/~hansha/

UniversityCollegeofSoutheastNorway

www.usn.no

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