Introduction to Visual Studio and C

Transcription

UniversityCollegeofSoutheastNorway
IntroductiontoVisual
StudioandC#
HANS-PETTERHALVORSEN,2016.09.26
http://home.hit.no/~hansha
TableofContents
1.
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
2
3
TableofContents 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
Tutorial:IntroductiontoVisualStudioandC#
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
1. Introduction
InthisTutorialwewilluseVisualStudioandC#.C#istheprogramminglanguage,while
VisualStudioisthedevelopmentenvironment.
Usefullinks:
VisualStudio:http://msdn.microsoft.com/en-us/library/dd831853.aspx
C#:http://msdn.microsoft.com/en-us/library/kx37x362.aspx 1.1.
VisualStudio
MicrosoftVisualStudioisanintegrateddevelopmentenvironment(IDE)fromMicrosoft.It
canbeusedtodevelopconsoleandgraphicaluserinterfaceapplicationsalongwith
WindowsFormsapplications,websites,webapplications,andwebservicesinbothnative
codetogetherwithmanagedcodeforallplatformssupportedbyMicrosoftWindows,
WindowsPhone,WindowsCE,.NETFramework,.NETCompactFrameworkandMicrosoft
Silverlight.
Belowweseetheintegrateddevelopmentenvironment(IDE)inVisualStudio:
5
6
Introduction Newprojectsarecreatedfromthe“NewProject”window:
1.2.
C#
C#ispronounced“seesharp”.C#isanobject-orientedprogramminglanguageandpartof
the.NETfamilyfromMicrosoft.C#isverysimilartoC++andJava.C#isdevelopedby
MicrosoftandworksonlyontheWindowsplatform.
1.3.
.NETFramework
The.NETFramework(pronounced“dotnet”)isasoftwareframeworkthatrunsprimarilyon
MicrosoftWindows.Itincludesalargelibraryandsupportsseveralprogramminglanguages
whichallowlanguageinteroperability(eachlanguagecanusecodewritteninother
languages).The.NETlibraryisavailabletoalltheprogramminglanguagesthat.NET
supports.Programswrittenforthe.NETFrameworkexecuteinasoftwareenvironment,
knownastheCommonLanguageRuntime(CLR),anapplicationvirtualmachinethat
providesimportantservicessuchassecurity,memorymanagement,andexceptionhandling.
TheclasslibraryandtheCLRtogetherconstitutethe.NETFramework.
7
1.4.
Introduction Object-OrientedProgramming(OOP)
Object-orientedprogramming(OOP)isaprogramminglanguagemodelorganizedaround
"objects"ratherthan"actions"anddataratherthanlogic.Historically,aprogramhasbeen
viewedasalogicalprocedurethattakesinputdata,processesit,andproducesoutputdata.
ThefirststepinOOPistoidentifyalltheobjectsyouwanttomanipulateandhowthey
relatetoeachother,anexerciseoftenknownasdatamodeling.Onceyou'veidentifiedan
object,yougeneralizeitasaclassofobjectsanddefinethekindofdataitcontainsandany
logicsequencesthatcanmanipulateit.Eachdistinctlogicsequenceisknownasamethod.A
realinstanceofaclassiscalledan“object”oran“instanceofaclass”.Theobjectorclass
instanceiswhatyouruninthecomputer.Itsmethodsprovidecomputerinstructionsand
theclassobjectcharacteristicsproviderelevantdata.Youcommunicatewithobjects-and
theycommunicatewitheachother.
ImportantfeatureswithOOPare:
•
•
•
•
ClassesandObjects
Inheritance
Polymorphism
Encapsulation Simulawasthefirstobject-orientedprogramminglanguage.Simulawasdevelopedinthe
1960sbyKristenNygaardfromNorway.
Java,Python,C++,VisualBasic.NETandC#arepopularOOPlanguagestoday. SinceSimula-typeobjectsarereimplementedinC++,JavaandC#theinfluenceofSimulais
oftenunderstated.ThecreatorofC++(1979),BjarneStroustrup(fromDenmark),has
acknowledgedthatSimulawasthegreatestinfluenceonhimtodevelopC++.
2. VisualStudio
2.1.
Introduction
HomepageofVisualStudio:http://www.microsoft.com/visualstudio
ThereexistdifferentversionsofVisualStudio,suchasVisualStudioExpress(free),Visual
StudioProfessional,VisualStudioPremiumandVisualStudioUltimate.
2.2.
GettingStarted
2.2.1.
IntegratedDevelopmentEnvironment(IDE)
TheVisualStudioproductfamilysharesasingleintegrateddevelopmentenvironment(IDE)
thatiscomposedofseveralelements:theMenubar,Standardtoolbar,varioustoolwindows
dockedorauto-hiddenontheleft,bottom,andrightsides,aswellastheeditorspace.The
toolwindows,menus,andtoolbarsavailabledependonthetypeofprojectorfileyouare
workingin.
BelowweseetheVisualStudioIDE(IntegratedDevelopmentEnvironment):
8
9
2.2.2.
VisualStudio NewProject Thefirstthingyoudowhenyouwanttocreateanewapplicationistocreateanewproject.
ThiscanbedonefromtheStartPage:
OrfromtheFilemenu:
Thenthe“NewProject”windowappears:
10
VisualStudio Inthiswindowyouwillselectanappropriatetemplatebasedonwhatkindofapplicationyou
wanttocreate,andanameandlocationforyourprojectandsolution.
Themostcommonapplicationsare:
•
•
•
•
•
WindowsFormApplication
ConsoleApplication
WPFApplication
ASP.NETWebApplication
SilverlightApplication
2.2.3.
SolutionExplorer
Solutionsandprojectscontainitemsthatrepresentthereferences,dataconnections,
folders,andfilesthatyouneedtocreateyourapplication.Asolutioncontainercancontain
multipleprojectsandaprojectcontainertypicallycontainsmultipleitems.
11
VisualStudio 2.2.4.
Toolbox
TheToolboxcontainsallthenecessarycontrols,etc.youneedtocreateyouruserinterface.
SeeFigurebelow.
TheToolboxcontainsallthecontrols,etc.wecanuse
inouruserinterface.
Inordertousetheminouruserinterface,wejustdrag
anddropthemtothe“Form”,asshownbelow:
12
2.2.5.
VisualStudio 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: Tutorial:IntroductiontoVisualStudioandC#
14
VisualStudio Themostusedtoolis“StartDebugging”(ShortcutKey:F5).
3. WindowsProgramming
3.1.
Introduction
WhencreatingordinaryWindowsapplications,wecanselectbetweenthefollowing:
•
•
WindowsFormsApplication
WPFApplications(WindowsPresentationFoundation)
WindowsFormsisthestandardwayofcreatingWindowsapplicationsandhasexistedin
manyyears,evenbefore.NET1.0(2002)wasintroduced.WPFisanewapproachfrom
creatingWindowsapplicationsandwasintroducedwith.NETFramework3.0(2006).
ForexamplehastheVisualStudioIDEbeenentirelyrewrittenusingWPF.
WindowsFormsApplicationandWPFApplicationswillbeexplainedinmoredetailbelow.
3.1.1.
WindowsForms
WindowsFormsisthestandardwayofcreatingWindowsapplications.
Select“WindowsFormsApplication”inthe“NewProject”window:
15
16
3.1.2.
WindowsProgramming WPF
DevelopedbyMicrosoft,theWindowsPresentationFoundation(orWPF)isacomputersoftwaregraphicalsubsystemforrenderinguserinterfacesinWindows-basedapplications.
WPFisintendedtotakeoverforthetraditionalWindowsForms.
ThegraphicaluserinterfaceinWPFisdesignedusingXAML(ExtensibleApplicationMarkup
Language).
XAML:
Followingthesuccessofmarkuplanguagesforwebdevelopment,WPFintroducesanew
languageknownaseXtensibleApplicationMarkupLanguage(XAML),whichisbasedonXML.
XAMLisdesignedasamoreefficientmethodofdevelopingapplicationuserinterfaces
Select“WPFApplication”inthe“NewProject”window:
3.2.
HelloWorld
Westartbycreatingatraditional“HelloWorld”applicationusingWindowsForms.The
applicationisshownbelow:
17
WindowsProgramming TheVisualStudioIDElookslikethis:
InthisprojectweuseasimpleTextBox(textBox1)andwhenwestarttheprogramthetext
“HelloWorld”iswrittentotheTextBox.
Thecodeisasfollows:
using
using
using
using
using
using
using
using
System;
System.Collections.Generic;
System.ComponentModel;
System.Data;
System.Drawing;
System.Linq;
System.Text;
System.Windows.Forms;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
18
WindowsProgramming private void Form1_Load(object sender, EventArgs e)
{
textBox1.Text = "Hello World";
}
}
}
4. GettingStartedwithC#
C#isamodernObject-orientedprogramminglanguage.
Object-orientedprogramming(OOP)isaprogrammingparadigmusing"objects"–data
structuresconsistingofdatafieldsandmethodstogetherwiththeirinteractions–todesign
applicationsandcomputerprograms.Programmingtechniquesmayincludefeaturessuchas
dataabstraction,encapsulation,messaging,modularity,polymorphism,andinheritance. 4.1.
Introduction
Inthischapterwewillstartwiththebasicallprogramminglanguageshave:…
•
•
•
DataTypesandVariables
ControlFlow:If-Else,etc.
Loops:WhileLoops,ForLoops,etc.
Furtherwewillintroducethefollowing:
•
•
•
•
•
Namespaces
Classes
DataFields
Methods
Properties
InthenextchapterwewillgomoreindepthofwhatObject-orientedprogrammingisand
introducethefollowingimportantOOPtopics:
•
•
•
Inheritance
Polymorphism
Encapsulation Note!C#iscase-sensitive. 4.2.
DataTypesandVariables
19
20
GettingStartedwithC# “Variables”aresimplystoragelocationsfordata.Youcanplacedataintothemandretrieve
theircontentsaspartofaC#expression.Theinterpretationofthedatainavariableis
controlledthrough“Types”. TheC#simpletypesconsistof:
•
•
•
Booleantype
Numerictypes:Integrals,FloatingPoint,Decimal
Stringtype
4.2.1.
Booleantype
Booleantypesaredeclaredusingthekeyword“bool”.Theyhavetwovalues:“true”or
“false”.Inotherlanguages,suchasCandC++,booleanconditionscanbesatisfiedwhere0
meansfalseandanythingelsemeanstrue.However,inC#theonlyvaluesthatsatisfya
booleanconditionistrueandfalse,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:
21
GettingStartedwithC# 4.2.4.
Arrays
Example:
int[] myInts = { 5, 10, 15 };
4.3.
ControlFlow
Tobeabletocontroltheflowinyourprogramisimportantineveryprogramminglanguage.
Thetwomostimportanttechniquesare:
•
•
TheifStatement
TheswitchStatement
4.3.1.
TheifStatement
Theifstatementisprobablythemostusedmechanismtocontroltheflowinyour
application.
Anifstatementallowsyoutotakedifferentpathsoflogic,dependingonagivencondition.
Whentheconditionevaluatestoabooleantrue,ablockofcodeforthattrueconditionwill
execute.Youhavetheoptionofasingleifstatement,multipleelseifstatements,andan
optionalelsestatement.
Example:
bool myTest;
22
GettingStartedwithC# myTest=false;
if (myTest==false)
MessageBox.Show("Hello");
Ifwehavemorethanonelineofcodethatthatshallbeexecuted,weneedtousebraces,
e.g.:
bool myTest;
myTest=false;
if (myTest == false)
{
MessageBox.Show("Hello1");
}
Formorecomplexlogicweusetheif…elsestatement.
Example:
bool myTest;
myTest=true;
if (myTest == false)
{
}
else
{
}
Oryoucanusenestedif…elseifsentences.
Example:
int myTest;
myTest=2;
if (myTest == 1)
{
}
else if (myTest == 2)
{
}
else
{
}
4.3.2.
TheswitchStatement
Anotherformofselectionstatementistheswitchstatement,whichexecutesasetoflogic
dependingonthevalueofagivenparameter.Thetypesofthevaluesaswitchstatement
operatesoncanbebooleans,enums,integraltypes,andstrings.
23
GettingStartedwithC# Example:
switch (myTest)
{
case 1:
break;
case 2:
break;
default:
break;
}
4.4.
Loops
InC#wehavedifferentkindofloops:
•
•
•
•
Thewhileloop
Thedoloop
Theforloop
Theforeachloop
4.4.1.
ThewhileLoop
Awhileloopwillcheckaconditionandthencontinuestoexecuteablockofcodeaslongas
theconditionevaluatestoabooleanvalueoftrue.
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,exceptthatitchecksitsconditionattheendofthe
loop.Thismeansthatthedoloopisguaranteedtoexecuteatleastonetime.Ontheother
hand,awhileloopevaluatesitsbooleanexpressionatthebeginningandthereisgenerally
noguaranteethatthestatementsinsidetheloopwillbeexecuted,unlessyouprogramthe
codetoexplicitlydoso.
Example:
24
GettingStartedwithC# int myInt = 0;
do
{
myInt++;
} while (myInt < 10);
4.4.3.
TheforLoop
Aforloopworkslikeawhileloop,exceptthatthesyntaxoftheforloopincludes
initializationandconditionmodification.forloopsareappropriatewhenyouknowexactly
howmanytimesyouwanttoperformthestatementswithintheloop.
Example:
for (int i = 0; i < 10; i++)
{
myInt++;
}
4.4.4.
TheforeachLoop
Aforeachloopisusedtoiteratethroughtheitemsinalist.Itoperatesonarraysor
collections.
Example:
string[] names = { "Elvis", "Beatles", "Eagles", "Rolling Stones" };
foreach (string person in names)
{
MessageBox.Show(person);
}
4.5.
Methods
Methodsareextremelyusefulbecausetheyallowyoutoseparateyourlogicintodifferent
units.Youcanpassinformationtomethods,haveitperformoneormorestatements,and
retrieveareturnvalue.Thecapabilitytopassparametersandreturnvaluesisoptionaland
dependsonwhatyouwantthemethodtodo.
Methodsaresimilartofunctions,procedureorsubroutineusedinotherprogramming
languages.Thedifferenceisthatamethodisalwaysapartofaclass.
Example:
public void ShowCarColor(string color)
25
GettingStartedwithC# {
MessageBox.Show("My Car is: " + color);
}
WelearnmoreaboutmethodsintheClassessectionbelow.
Wehave2kindsofMethods:
•
•
StaticMethods
NonstaticMethods(InstanceMethod)
StaticMethodsbelongstothewholeclass,whilenonstaticMethodsbelongtoeachinstance
createdfromtheclass.
4.5.1.
NonstaticMethods
Example:
Wedefinetheclass:
class Car
{
//Nonstatic/Instance Method
public void SetColor(string 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);
}
}
26
GettingStartedwithC# Thenweuseit:
Boat.SetColor("green");
i.e.,wedon’tneedtocreateanobject/instantiatingtheclassbeforeweusetheStatic
Method.
4.6.
Namespaces
NamespacesareC#programelementsdesignedtohelpyouorganizeyourprograms.They
alsoprovideassistanceinavoidingnameclashesbetweentwosetsofcode.Implementing
Namespacesinyourowncodeisagoodhabitbecauseitislikelytosaveyoufromproblems
laterwhenyouwanttoreusesomeofyourcode.
YouspecifytheNamespacesyouwanttouseinthetopofyourcode.
Example:
WhenyoucreateanewWindowsFormsapplication,thefollowingdefaultnamespaceswill
beincluded.
using
using
using
using
using
using
using
using
…
System;
System.Data;
System.Drawing;
System.Linq;
System.Text;
Itisjusttoaddmorewhenyouneedit.
MoreaboutNamespaceslater.
4.7.
Classes
ThefirststepinOOPistoidentifyalltheobjectsyouwanttomanipulateandhowthey
relatetoeachother,anexerciseoftenknownasdatamodeling.Onceyou'veidentifiedan
object,yougeneralizeitasaclassofobjectsanddefinethekindofdataitcontainsandany
logicsequencesthatcanmanipulateit.Eachdistinctlogicsequenceisknownasamethod.A
realinstanceofaclassiscalledan“object”oran“instanceofaclass”.Theobjectorclass
instanceiswhatyouruninthecomputer.Itsmethodsprovidecomputerinstructionsand
theclassobjectcharacteristicsproviderelevantdata.Youcommunicatewithobjects-and
theycommunicatewitheachother.
27
GettingStartedwithC# EverythinginC#isbasedonClasses.Classesaredeclaredbyusingthekeywordclass
followedbytheclassnameandasetofclassmemberssurroundedbycurlybraces. AclassnormallyconsistsofMethods,FieldsandProperties.
Everyclasshasaconstructor,whichiscalledautomaticallyanytimeaninstanceofaclassis
created.Thepurposeofconstructorsistoinitializeclassmemberswhenaninstanceofthe
classiscreated.Constructorsdonothavereturnvaluesandalwayshavethesamenameas
theclass.
Example:
Wedefinethefollowingclass:
class Car
{
public string color; //Field
//Method
public void ShowCarColor()
{
}
}
Thenwecanuseit:
myCar.color = "blue"; //We set a value for the color Field
myCar.ShowCarColor(); //We call the Method
Theresultisasfollows:
4.7.1.
Constructor
Thepurposeofconstructorsistoinitializeclassmemberswhenaninstanceoftheclassis
created.
Example:
WecanuseaConstructortocreatea“default”colorforourcar.
Wedefinetheclass:
28
GettingStartedwithC# class Car
{
//Constructor - Used to initialize the Class
public Car()
{
color="green";
}
//Method
{
}
}
Thenwecanuseit:
myCar.color = "blue"; //We set a value for the color Field
Theresultsareasfollows:
…
Example:
Wecanalsodothefollowing:
class Car
{
//Constructor - Used to initialize the Class
public Car(string initColor)
{
color = initColor;
29
GettingStartedwithC# }
//Method
{
}
}
Thenweuseit:
Car myCar = new Car("green"); //We create an Instance of the Class
Newfeature:InitializationanobjectwithoutaConstructor:
InC#4.0wecandothefollowing:
WedefinetheClass(withoutanycontructor):
class Car
{
public string model; //Field
//Method
{
MessageBox.Show("My Car Color is: " + color);
MessageBox.Show("My Car Model is: " + model);
}
}
Thenwedothefollowing:
Car myCar = new Car {color="white", model="2004"};
4.8.
Properties
Propertiesprovidetheopportunitytoprotectafieldinaclassbyreadingandwritingtoit
throughtheproperty.Inotherlanguages,thisisoftenaccomplishedbyprograms
implementingspecializedgetterandsettermethods.C#propertiesenablethistypeof
protectionwhilealsolettingyouaccessthepropertyjustlikeitwasafield. Example:
WedefineaClasswithPropertiesandaMethod:
class Car
{
30
GettingStartedwithC# 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,and
Constructors.Hereisacompletelistofthetypesofmembersyoucanhaveinyourclasses: •
•
•
•
•
•
•
•
•
Constructors
Destructors(oppositeofConstructors)
Fields
Methods
Properties
Indexers
Delegates
Events
NestedClasses
31
4.9.
GettingStartedwithC# NamingConvention
Thereisdifferentnameconventionforhowtospecifyyourvariables,classesandMethods,
etc.
Camelnotation:
Forvariablesandparameters/argumentswenormallyuse“Camelnotation”.
Examples:
string myCar;
int number;
string backColor;
→InCamelcasingthefirstletterofanidentifierislowercaseandthefirstletterofeach
subsequentconcatenatedwordiscapitalized.
Pascalnotation:
Forclasses,methodsandproperties,wenormallyuse“Pascalnotation”.
Examples:
class Car
{
void ShowCarColor()
{
…
}
}
→InPascalcasingthefirstletterintheidentifierandthefirstletterofeachsubsequent
concatenatedwordarecapitalized.
ForNamespacesweusePascalcasingandadotseparator.
Examples:
System.Drawing
System.Collections.Generics
Controls:
Forcontrolsonyouruserinterfaceweeitheruse“Pascalnotation”or“Hungariannotation”,
butsticktooneofthem!
Examples:
“Pascalnotation”:
LoginName
LoginPassword
32
GettingStartedwithC# “Hungariannotation”:
txtName
txtPassword
lblName
btnCancel
Where“txt”meansitisaTextControl,“lbl”aLabelControl,“btn”aButtonControl,etc.
Acronyms:
Casingofacronymsdependsonthelengthoftheacronym.Allacronymsareatleasttwo
characterslong.Ifanacronymisexactlytwocharacters,itisconsideredashortacronym.An
acronymofthreeormorecharactersisalongacronym.
Ingeneral,youshouldnotuseabbreviationsoracronyms.Thesemakeyournamesless
readable.Similarly,itisdifficulttoknowwhenitissafetoassumethatanacronymiswidely
recognized.
Butifyoumust,therulesareasfollows:
ShortacronymExamples(twocharacters):
DBRate
ApropertynamedDBRateisanexampleofashortacronym(DB)usedasthefirstwordofa
Pascal-casedidentifier. ioChannel
AparameternamedioChannelisanexampleofashortacronym(IO)usedasthefirstword
ofacamel-casedidentifier.
LongacronymExamples(threeormorecharacters):
XmlWriter
AclassnamedXmlWriterisanexampleofalongacronymusedasthefirstwordofaPascalcasedidentifier. htmlReader
AparameternamedhtmlReaderisanexampleofalongacronymusedasthefirstwordofa
camel-casedidentifier.
5. MoreObject-oriented
Techniques
InthischapterwewillintroducethefollowingObject-orientedtechniques:
•
•
•
Inheritance
Polymorphism
Encapsulation 5.1.
Inheritance
Inheritanceisoneoftheprimaryconceptsofobject-orientedprogramming.Itallowsyouto
reuseexistingcode.Througheffectiveemploymentofreuse,youcansavetimeinyour
programming. Example:
WedefinetheBaseclass:
class Car
{
public void SetColor(string 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();
33
34
MoreObject-orientedTechniques myVolvo.SetColor("green");
Asyoucanseewecanusethe“SetColor()”MethodthathasbeendefinedintheBaseClass.
5.2.
Polymorphism
Anotherprimaryconceptofobject-orientedprogrammingisPolymorphism.Itallowsyouto
invokederivedclassmethodsthroughabaseclassreferenceduringrun-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
{
{
MessageBox.Show("I am a Ford");
}
}
class Toyota : Car
{
{
MessageBox.Show("I am a Toyota");
}
}
These3classesinherittheCarclass.EachclasshasaCarType()methodandeachCarType()
methodhasanoverridemodifier.Theoverridemodifierallowsamethodtooverridethe
virtualmethodofitsbaseclassatrun-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.
Encapsulation
Encapsulationmeansthattheinternalrepresentationofanobjectisgenerallyhiddenfrom
viewoutsideoftheobject'sdefinition.Typically,onlytheobject'sownmethodscandirectly
inspectormanipulateitsfields.
WecansetdifferentAccessrightsonClassesandMethods:
6. ExceptionHandling
Inprogrammingerrorandexceptionhandlingisveryimportant.C#hasbuilt-inandreadyto
usemechanismtohandlethis.Thismechanismisbasedonthekeywordstry,catch,throw
andfinally.
Exceptionsareunforeseenerrorsthathappeninyourprograms.Mostofthetime,youcan,
andshould,detectandhandleprogramerrorsinyourcode.Forexample,validatinguser
input,checkingfornullobjects,andverifyingthevaluesreturnedfrommethodsarewhat
youexpect,areallexamplesofgoodstandarderrorhandlingthatyoushouldbedoingallthe
time. However,therearetimeswhenyoudon'tknowifanerrorwilloccur.Forexample,youcan't
predictwhenyou'llreceiveafileI/Oerror,runoutofsystemmemory,orencountera
databaseerror.Thesethingsaregenerallyunlikely,buttheycouldstillhappenandyouwant
tobeabletodealwiththemwhentheydooccur.Thisiswhereexceptionhandlingcomesin. Whenexceptionsoccur,theyaresaidtobe“thrown”.C#usesthekeywordstry,catch,throw
andfinally.Itworkslikethis:Amethodwilltrytoexecuteapieceofcode.Ifthecodedetects
aproblem,itwillthrowanerrorindication,whichyourcodecancatch,andnomatterwhat
happens,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();
36
37
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();
}
}
ExceptionHandling 7. WindowsForms
Example
Inthischapterwewillgothroughalargeexample.Inthisexamplewewillcreatean
applicationinVisualStudiothatcontrolsthefollowingwatertankprocess:
Thepurposeistocontrolthelevelinthewatertank.Inordertocommunicatewiththe
physicalprocess,weuseaNIUSB-6008DAQdevice:
Wewillnotshowallthedetailsinthecode,butfocusonthestructure.
BelowweseetheuserinterfacewehavecreatedinVisualStudio:
38
39
WindowsFormsExample BelowweseetheVisualStudioproject:
Westartwithdefiningtheclassesweneedinourapplication.
IntheSolutionExplorerwehavedefineda“Classes”folderwhereweputalltheclasseswe
create:
40
WindowsFormsExample Inordertocreatenewclassesweright-clickintheSolutionExplorerandselect“Add-New
Item…”:
NextweselecttheClassiteminthe“AddNewItem”window:
41
WindowsFormsExample 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(...)
{
...
}
}
}
42
WindowsFormsExample Itisgoodpracticetocreateanewfileforeachnewclasswedefine.Thenwestartby
definingameaningfulNamespace.NextwedefineourClasswithnecessaryFields,
PropertiesandMethods.
WealsoneedtoincludethenecessaryNamespaceourClasswillneed.Inthisexamplewe
haveincludedsome3.partyAssembliesfromNationalInstruments:
using NationalInstruments;
using NationalInstruments.DAQmx;
TheseAssembliescontainsthedrivertotheNIUSB-6008DAQdeviceweareusing.
TheAssembliesweusemustbeaddedinthe“References”folderintheSolutionExplorer:
MainApplication:
InourmainapplicationwestartwithincludingourNamespace:
using
using
using
using
using
using
using
using
using
using
using
using
NationalInstruments;
NationalInstruments.UI;
NationalInstruments.UI.WindowsForms;
System;
System.Data;
System.Drawing;
System.Linq;
System.Text;
Tuc.Control;
namespace Control_Application
{
public partial class Form1 : Form
{
...
}
}
43
WindowsFormsExample Itisalsoagoodideatocreatedifferentregionsinordertostructureyourcodebetter.This
canbedonelikethis:
//Comment
# region
... //Your Code
# endregion
InthiswayourMainApplicationmaylooklikethis:
8. WebProgramming
8.1.
Introduction
TodaymostoftheapplicationsfocusontheInternet,wheretheapplicationscanbeviewed
inastandardWebBrowser.StaticWebpagesarebasedonHTMLandCSS.Inordertocreate
moreadvancedapplications,weneedmorepowerfultools.
Importantframeworksandtoolsforcreatingdynamicwebpages:
•
•
•
•
ASP.NET
AJAX/ASP.NETAJAX
JavaScript
Silverlight
Theseframeworksandtoolswillbeexplainedbelow.
SeetheTutorial“ASP.NETandWebProgramming”formoredetails.
8.2.
HTML
HTML,whichstandsforHyperTextMarkupLanguage,isthepredominantmarkuplanguage
forwebpages.HTMListhebasicbuilding-blocksofwebpages.
HTMLiswrittenintheformofHTMLelementsconsistingoftags,enclosedinanglebrackets
(like<html>),withinthewebpagecontent.HTMLtagsnormallycomeinpairslike<h1>and
</h1>.Thefirsttaginapairisthestarttag,thesecondtagistheendtag(theyarealso
calledopeningtagsandclosingtags).Inbetweenthesetagswebdesignerscanaddtext,
tables,images,etc.
8.3.
WebBrowser
ThepurposeofawebbrowseristoreadHTMLdocumentsandcomposethemintovisualor
audiblewebpages.ThebrowserdoesnotdisplaytheHTMLtags,butusesthetagsto
interpretthecontentofthepage.
44
45
WebProgramming TodaywehavethefollowingmajorWebBrowsers:
•
•
•
•
•
InternetExplorer(byMicrosoft)
Firefox(byMozilla)
Chrome(byGoogle)
Safari(byApple)
Opera(byOperafromNorway)
8.4.
CSS
WebbrowserscanalsorefertoCascadingStyleSheets(CSS)todefinetheappearanceand
layoutoftextandothermaterial. TheW3C,maintainerofboththeHTMLandtheCSSstandards
8.5.
JavaScript
JavaScriptisanobject-orientedscriptinglanguagebasicallyusedtocreatedynamicweb
pages.JavaScriptisprimarilyusedintheformofclient-sideJavaScript,implementedaspart
ofawebbrowserinordertoprovideenhanceduserinterfacesanddynamicwebsites.
8.6.
ASP.NET
ASP.NETisawebapplicationframeworkdevelopedbyMicrosofttoallowprogrammersto
builddynamicwebsites,webapplicationsandwebservices. ASP.NETispartoftheVisualStudiopackage
ItwasfirstreleasedinJanuary2002withversion1.0ofthe.NETFramework,andisthe
successortoMicrosoft'sActiveServerPages(ASP)technology.ASP.NETisbuiltonthe
CommonLanguageRuntime(CLR),allowingprogrammerstowriteASP.NETcodeusingany
supported.NETlanguage,suchasC#andVB.NET.
ASP.NETwebpagesorwebpage,knownofficiallyasWebForms],arethemainbuildingblock
forapplicationdevelopment.Webformsarecontainedinfileswithan“.aspx”extension.
Select“ASP.NETApplication”inthe“NewProject”window:
46
WebProgramming 8.7.
AJAX/ASP.NETAJAX
AJAXisanacronymforAsynchronousJavaScriptandXML.AJAXisagroupofinterrelated
webdevelopmentmethodsusedontheclient-sidetocreateinteractivewebapplications.
WithAjax,webapplicationscansenddatato,andretrievedatafrom,aserver
asynchronously(inthebackground)withoutinterferingwiththedisplayandbehaviorofthe
existingpage.
ASP.NETAJAXisasetofextensionstoASP.NETdevelopedbyMicrosoftforimplementing
AJAXfunctionality.
8.8.
Silverlight
MicrosoftSilverlightisanapplicationframeworkforwritingandrunningbrowserplug-insor
otherrichinternetapplications,withfeaturesandpurposessimilartothoseofAdobeFlash.
Therun-timeenvironmentforSilverlightisavailableasaplug-informostwebbrowsers.
SilverlightisalsooneofthetwoapplicationdevelopmentplatformsforWindowsPhone7/8.
ThelatestversionisSilverlight5.0.
SilverlightisbasedonWPF,soinSilverlightapplications,userinterfacesaredeclaredin
ExtensibleApplicationMarkupLanguage(XAML)andprogrammedusingasubsetofthe.NET
Framework.
9. DatabaseProgramming
Mostoftoday’sapplicationsuseabackenddatabasetostoreimportantdata,e.g.,Facebook,
Twitter,etc.
InordertousedatabasesinourapplicationsweneedtoknowStructuredQuerylanguage
(SQL).FormoreinformationaboutSQL,seethefollowingTutorial:
StructuredQueryLanguage(SQL)
Inadditionyouneedtoknowaboutdatabasesystems.Wehavedifferentkindofdatabase
systemsandlotsofdifferentvendors.SincethisTutorialisaboutVisualStudioandC#,we
willuseMicrosoftSQLServer.Formoreinformationaboutdatabasesystemsingeneraland
speciallySQLServer,seethefollowingTutorial:
IntroductiontoDatabaseSystems TheTutorialsareavailablefrom:http://home.hit.no/~hansha 9.1.
ADO.NET
ADO.NET(ActiveXDataObjectfor.NET)isasetofcomputersoftwarecomponentsthat
programmerscanusetoaccessdataanddataservices.Itisapartofthebaseclasslibrary
thatisincludedwiththeMicrosoft.NETFramework.Itiscommonlyusedbyprogrammersto
accessandmodifydatastoredinrelationaldatabasesystems,thoughitcanalsoaccessdata
innon-relationalsources.
47
Hans-PetterHalvorsen,M.Sc.
E-mail:[email protected]
Blog:http://home.hit.no/~hansha/
UniversityCollegeofSoutheastNorway
www.usn.no

Introduction to Visual Studio and C

Transcription

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