Session 11_TP 6

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Session 6

Advanced C# Concepts -

II

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C# Simplifed / Session 6 / 2 o 44

Review An assembly consists o:

A set o types and resources tat orm a lo!ical unit ounctionality"

A maniest containin! inormation tat describes teassembly" e can deploy classes witin te same namespace into

di$erent assemblies% and classes witin di$erentnamespaces into one assembly"

Assemblies are o two types: &rivate Assemblies and Sared

Assemblies 'e version number o an assembly is represented as a our(

part number in te ollowin! ormat: ...

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Review Contd* 'e Sstem.Re!ection namespace contains around orty

classes and interaces tat can be employed to !etinormation about an ob+ect"

Collections are datatypes tat provide us wit a way to storeand collectively act upon data"

,-ceptions are raised by te runtime wen an error occurs" 'e try and catc bloc. elps in andlin! raised e-ceptions" sin! te 'row statement% we can eiter trow a system

e-ception% or our own custom e-ception" 'e statements in te 0inally bloc. are e-ecuted re!ardless

o te control 1ow"

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b+ectives Explain Properties

Discuss type of properties such as

Public Private

Read-only

Write-only

Discuss Indexers

Implement Delegates

Dene and Raise Events

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&roperties in C# C# provides te acility to protect a feld

in a class by readin! and writin! to it

trou! a eature called properties C# properties enable a similar type o

protection wile at te same time allowsaccess to te property li.e a feld"

5n !eneral terms% a property would meante caracteristics or inormation abouta particular entity"

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&roperties in C# ( Contd 'e !eneral orm or declarin! te properties is

access7modifer8 return7type8property7name89"et9set9

were access7modifer8 can be private% public%protectedor internal" 'e return7type8 can beany valid C# type"

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&roperties < =et > Setpublic class Employee

{

private String sName

private String sId public string sId

{

get

{

return sId;

} set

{

sId = value

}

}

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&roperties < =et > Set

}

Employee emp = new Employee();

empsId = !S""#!;

$onsole%rite&ine('e student id is

{"}!* empsId);

,ac time we need to access te feld weneed to call te set and !et metods

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&roperties ( ,-ampleusing System;public class Student

{

public string sName; ++,ield

private string internal-sId;++,ieldpublic string sId ++.roperty {

get

{

return internal_sId;

} set

{

internal_sId = value;

}

}

}

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&roperties < ,-ample Contd*

class est

{

static void /ain()

{

Student one = new Student();

onesName = 'Sam'; one.sId = "St423";

Console.Writeine!"#e $a%e o& t#e Student is {'}

and #is Id is {(}") one.s$a%e) one.sId*;

}

}

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&roperties ( ,-planation

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'ypes o &roperties ublic roperties: sers can access tese

properties witout any restrictions rivate roperties: are accessible to te

users only rom inside te class or structurewere tey are defned"

Read $ %rite ropert: &rovides bot readand write access to te data members"

Read - &nl ropert: &rovides only readaccess to te data members"

%rite - &nl ropert: &rovides only writeaccess to te data members"

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Read(only &roperty ( ,-amplepublic class Employee

{

private int empsalary = #0"""; ++,ield

public int EmpSalary ++.roperty

{ get

{

return empsalary;

}

}

}

class Employeeest

{

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Read(only &roperty (

utputstatic void /ain()

{

Employee ob1Employee = new Employee();

System$onsole%rite&ine ("e salary o2 te

Employee is {"}"* ob1EmployeeEmpSalary);ob1EmployeeEmpSalary = 30"""; ++error }

}

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&roperties s 0ields &roperties are lo!ical felds

&roperties are an e-tension ofelds

nli.e felds% properties do notcorrespond directly to astora!e location

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&roperty Accessors Accessors o properties contain te

statements tat are to be e-ecuted wena property is "et/set

'e accessor declarations can contain te"etaccessor or te setaccessor or bot"

'e "etaccessor is similar to any

metod tat returns a value 'e setaccessor is similar to a metod

tat returns a void

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5nde-ers 5nde-ers are simple components o C#

Created or arrays so tat te elements

are accessed directly by speciyin! teinde- rom te class ob+ect

Allow an ob+ect to be inde-ed in te

same way as an array ,nable array(li.e access to te

members o te class

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5nde-ers ( ,-ampleclass Inde4erE4ample{

public string56 string&ist =new string5#"6;

public string tis5int inde46

{ get

{

return string&ist5inde46;

}

set{

string&ist5inde46 = valueoString();

}

}

}

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5nde-ers ( utputclass est

{

static void /ain()

{ Inde4erE4ample inde4est = new Inde4erE4ample();

inde4eststring&ist5#6='Sam';

inde4est536='om';

System$onsole%rite&ine('inde4est5#6 is

{"}7ninde4est536 is {#}'* inde4est5#6* inde4est536);

}}

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Steps or declarin! an 5nde-er 'e access modifer tat decides te

visibility o te inde-er is to be mentioned

State te return type o te inde-er 'e t'is.eyword Speciy te data type o te inde-

State te variable name or te inde- Speciy te "etand setaccessors inside

te inde-er

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Rules or defnin! an 5nde-er

At least one 5nde-er parametermust be specifed

'e parameters sould beassi!ned values

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5nde-ers vs" Arrays 5nde-ers do not point to memory

locations

5nde-ers can ave non < inte!ersubscripts Dinde-esE

5nde-ers can be overloaded

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C# Simplifed / Session 6 / 2) o 4

5nde-er < ,-ample using System$ollections;

class StrInde4

{

public 8astable student&ist = new 8astable();

public int tis5string name6 {

get

{

return (int) student&ist5name6;

}

set {

student&ist5name6 = value;

}

}

}

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5nde-er < ,-ample

Contd*class est{

static void /ain()

{

StrInde4 ob1Inde4 = new StrInde4(); ob1Inde4 5'Sam'6 = 393::;

ob1Inde4 5'om'6 =

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5nde-er ,-ample ( 2using System$ollections;

class Inde4erE4ample

{

public string56 string&ist = new string5#"6;

public string tis5int inde46

{

get

{

return string&ist5inde46;

} set

{

string&ist5inde46 = valueoString();

}

}

public 8astable student&ist = new 8astable();

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5nde-er ,-ample < 2

Contd*public int tis5string number6

{

get

{ return (int) student&ist 5number6;

}

set

{

student&ist 5number6 = value;

}

}

}

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C# Simplifed / Session 6 / 2; o 4

5nde-er ,-ample < 2

Contd*class est

{

static void /ain()

{

Inde4erE4ample inde4est = new Inde4erE4ample();

inde4eststring&ist5#6 = 'Sam';

inde4est536 = 'om';

inde4est 5'Sam'6 = 393;

inde4est 5'om'6 =

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sin! Fultiple &arameters Fore tan one inde-er parameter can be specifed in an inde-er Fultiple parameters would mean tat te inde-er would be

accessed li.e a multi(dimensional array

class est/ultip

{

public int tis5int 2irst.* int second.6

{

++et and Set >ccessors appear ere

}

}

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sin! Fultiple &arameters

{

void static /ain()

{

est/ultip myest = new est/ultip();

int I = myest5#*#6; }

}

Class 'est5nde-ers wit multiple inde-erparameters are accessed li.e a Fulti(Gimensional Array"

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C# Simplifed / Session 6 / )B o 4

Gele!ates Contain a reerence to a metod Helps us decide% wic metod to call at

runtime 'ecnically% a dele!ate is a reerencetype used to encapsulate a metod wita specifc si!nature and return type"

Steps < Gefnin! a dele!ate 5nstantiatin! a dele!ate sin! a dele!ate

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Gefnin! Gele!ates

public delegate void

?elegateName();

Gefnin! a dele!ate involves speciyin! tereturn types and parameters tat eac metodmust provide

"""public delegate int Call+unctions !int a) int b*;

"""

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5nstantiatin! Gele!atesclass 'estGele!ates9 public dele!ate int Call0unctionsDint a% int bEI class Fatsperations 9 public int Fultiply0nDint a% int bE 9 return aJbI public int Givision0nDint a% int bE 9 return a/bI

5nstantiatin! adele!atemeans ma.in!

it point DorreerE to somemetod"

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5nstantiatin! Gele!ates

Contd*class est

{

static void /ain()

{ Call+unctions ,elegate-b;

/at#s-perations %at# = ne0

/at#s-perations!*;

,elegate-b = ne0

Call+unctions!%at#./ultipl1+un*; }

}

}

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sin! Gele!atesclass est?elegates{

public delegate int $all,unctions(int num#* int

num3);

class /ats@perations {

public int /ultiply,n(int num#* int num3)

{

return num#Anum3;

}

public int ?ivision,n(int num#* int num3) {

return num#+num3;

}

}

}

sin! a dele!ate means instantiatin! a metod tat usesdele!ates"

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sin! Gele!ates ( Contdclass est{

static void /ain()

{

$all,unctions ?elegate@b1; /ats@perations mat = new /ats@perations();

?elegate@b1 = new $all,unctions(mat/ultiply,n);

int result=?elegate@b1(0* 9);

System$onsole%rite&ine ('e Besult a2ter

calling /ultiply,n is C {"}'*result);

}?elegate@b1 = new $all,unctions(mat?ivision,n);

int result( = ,elegate-b!) 3*;

System$onsole%rite&ine ('e Besult a2ter

calling ?ivision,n is C {"}7n'*result#);

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sin! Gele!ates ( utput

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C# Simplifed / Session 6 / ); o 4

,vents ,vents in C# allow an ob+ect to notiy oter ob+ects

about te event or tat a can!e as occurred

'e ob+ect tat notifes te oters about te eventis .nown as te &ubliser

An ob+ect tat re!isters to an event is .nown aste Subscriber

Steps Gefnin! an ,vent Subscribe ob+ects to tat event Kotiy subscribers o te event

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C# Simplifed / Session 6 / )? o 4

Gefnin! ,vents ile defnin! an event te publiser

defnes a dele!ate

defnes an event based on te dele!ate

public delegatevoid delegate/e();private eventdelegate/e event/e;

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Subscribin!Subscribin! an ob+ect to an eventdepends upon te e-istence o te

event

event/e = ne0 delegate/e!ob./et#od*;

event/e = ne0 delegate/e!ob5./et#od*;

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Kotiyin!'o notiy all te ob+ects tat avesubscribed to an event we +ust need

to raise te eventiDconditionE9 eventMe()*

Raisin! an event is li.e callin! a

metod"

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,vents and Gele!ates(,-ample

using System;

class $lass>

{

public void ?isp/etod()

{

$onsole%rite&ine ('$lass > as been noti2ied o2

Noti2yEvery@ne EventD');

}

}

class $lass

{ public void ?isp/etod()

{

$onsole%rite&ine ('$lass as been noti2ied o2

Noti2yEvery@ne EventD');

}

}

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,vents and Gele!ates(

,-ampleclass est

{

public static void /ain()

{

est?elegate d> = new est?elegate(); $lass> ob1> = new $lass>();

$lass ob1 = new $lass();

d>Noti2yEvery@ne F= new

est?elegate/e?elegate (ob1>?isp/etod);

d>Noti2yEvery@ne F= new

est?elegate/e?elegate (ob1?isp/etod); d>Noti2y();

}

}

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C# Simplifed / Session 6 / 4) o 4

,vents and Gele!ates(

,-ampleclass est?elegate{

public delegate void /e?elegate();

public event /e?elegate Noti2yEvery@ne;

public void Noti2y(){

i2(Noti2yEvery@ne D= null)

{

$onsole%rite&ine ('Baise Event C ');

Noti2yEvery@ne();

}}

}

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Summary &roperties provide te opportunity to protect a feld in a class by

readin! and writin! it usin! accessors" An inde-er allows an ob+ect to be inde-ed in te same way as an

array" A dele!ate contains a reerence to a metod rater tan te metod

name" 'ere are tree steps involved in usin! dele!ates tat are as ollows"

+e,nin" a Gele!ate Instantiatin" a Gele!ate sin" a Gele!ate

,vents in C# allow an ob+ect to notiy oter ob+ects about te event%or about a can!e tat as occurred"

'ere are tree steps involved to andle events in C# tat are asollows" +e,nin" an vent Subscribin" objects to t'at event Noti/in" subscribers o/ t'e event (0'en it occurs)

Session 11_TP 6

Documents

Transcript of Session 11_TP 6