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Cursul de programare orientata

pe obiecte

Seria 14

Saptamana 2, 24 feb 2015Andrei Paun

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Principiile programarii orientate pe

obiecte !biecte

Clase

"ostenire

Ascunderea informatiei

Polimorfism Sabloane

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!biecte

au stare si actiuni #metode$functii%

au interfata #actiuni% si o parte ascunsa

#starea%

Sunt grupate in clase, obiecte cu aceleasi

proprietati

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Clase

mentionea&a proprietatile generale ale

obiectelor din clasa respecti'a

clasele nu se pot (rula)

folositoare la encapsulare #ascunderea

informatiei%

reutili&are de cod: mostenire

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"ostenire

multe obiecte au proprietati similare

reutili&are de cod

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Polimorfism

tot pentru claritate$ cod mai sigur

Polimorfism la compilare: e*+ ma*#int%,

ma*#float%

Polimorfism la e*ecutie: -

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Sabloane

din nou cod mai sigur$reutili&are de cod

putem implementa lista inlantuita de

.intregi

.caractere

.float

.obiecte

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Pri'ire de ansamblu pentru C//

arne Stroustrup in 13 la ell

aboratories in "urra 6ill, 7e8 9erse

5 re'i&ii: 15, 10, 1 A7S-/-S!,

200; #corrigendum%, 2011 #C//11%, include ?iostream@

using namespace std

int main#%

B int i

cout ?? Dis is output+En $$ tDis is a single line comment

$F ou can still use C stle comments F$

$$ input a number using @@

cout ?? nter a number:

cin @@ i

$$ no8, output a number using ??

cout ?? i ?? sHuared is ?? iFi ?? En

return 0I

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Jiferente cu C

?iostream@ #fara +D%

int main#% #fara 'oid%

using namespace std

cout, cin #fara K%

$$ comentarii pe o linie declarare 'ariabile

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>include ?iostream@

using namespace std

int main# %B

float f

cDar strL0M

double d cout ?? nter t8o floating point numbers:

cin @@ f @@ d

cout ?? nter a string:

cin @@ str

cout ?? f ?? ?? d ?? ?? str return 0

I

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citirea stringNurilor se face pana la primul

caracter alb

se poate face afisare folosind toate

caracterele speciale En, Et, etc+

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=ariabile locale

$F -ncorrect in C+ !O in C//+ F$

int f#%

B

int i

i 10 int $F 8onQt compile as a C program F$

iF2

return

I

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>include ?iostream@

using namespace std

int main#%

B

float f

double d

cout ?? nter t8o floating point numbers:

cin @@ f @@ d cout ?? nter a string:

cDar strL0M $$ str declared Dere, ust before 1st use

cin @@ str

cout ?? f ?? ?? d ?? ?? str

return 0

I

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C// 'ecDi 's C// nou

fara con'ersie automata la int

nou tip de include

using namespace

func#int i%

B return iFi

I

int func#int i%

B return iFi

I

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ipul de date bool

se definesc true si false #1 si 0%

C nu il defineste ca bool ci ca Rool #fara

true$false%

?stdbool+D@ pentru compatibilitate

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2 'ersiuni de C// diferente:

7oile include ?iostream@ ?fstream@ ?'ector@ ?string@

math.h este

string.h este

math.h deprecated, folositi cmath

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Clasele in C//

init#%, pusD#%, pop#% sunt functii membru

stc, tos: 'ariabile membru

>define S-T 100$$ Dis creates tDe class stac+

class stac B

int stcLS-TM

int tospublic:

'oid init#%

'oid pusD#int i%

int pop#%

I

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se creea&a un tip nou de date

un obiect instantia&a clasa

functiile membru sunt date prin semnatura

pentru definirea fiecarei functii se foloseste ::

stac mstac

'oid stac::pusD#int i%

B if#tosS-T% B

cout ?? Stac is full+En

return

I

stcLtosM i

tos//I

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:: scope resolution operator

si alte clase pot folosi numele pusD#% si pop#%

dupa instantiere, pentru apelul pusD#%

mstac+pusD#5% programul complet in continuare

stac mstac

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ncapsulare

urmatorul cod nu poate fi folosit in main#%

stac1+tos 0 $$ rror, tos is pri'ate+

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!'erloading de functii

polimorfism

simplicitate$corectitudine de cod

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#include

using namespace std;

// abs is overloaded three ways

int absint i!;

double absdouble d!;long abslong l!;

int main!

"

cout

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o'erload de functii

nume acelasi

diferenta e in tipurile de parametrii

tipul de intoarcere nu e suficient pentru

diferenta

se poate folosi si pentru functii complet

diferite #nerecomandat%

o'erload de operatori: mai tar&iu

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"ostenirea

incorporarea componentelor unei clase in

alta

refolosire de cod

detalii mai subtile pentru tipuri si subtipuri

clasa de ba&a, clasa deri'ata

clasa deri'ata contine toate elementele

clasei de ba&a, mai adauga noi elemente

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class building "

int rooms;

int floors;

int area;

public

void set-roomsint num!; int get-rooms!;

void set-floorsint num!;

int get-floors!;

void set-areaint num!;

int get-area!;

*;

// house is derived from building

class house public building "

int bedrooms;

int baths;

public void set-bedroomsint num!;

int get-bedrooms!;

void set-bathsint num!;

int get-baths!;

*;

tip acces: public, pri'ate, protected

mai multe mai tar&iu

public: membrii publici ai building

de'in publici pentru Douse

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Douse 7U are acces la membrii pri'ati ai lui

building

asa se reali&ea&a encapsularea

clasa deri'ata are acces la membrii publici

ai clasei de ba&a si la toti membrii sai

#publici si pri'ati%

#include

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#include iostream

using namespace std;

class building "

int rooms;

int floors;

int area;public

void set-roomsint num!;

int get-rooms!;

void set-floorsint num!;

int get-floors!;

void set-areaint num!;

int get-area!;

*;

// house is derived from building

class house public building "

int bedrooms;

int baths;public

void set-bedroomsint num!;

int get-bedrooms!;

void set-bathsint num!;

int get-baths!;

*;

// school is also derived from building

class school public building "

int classrooms;

int offices;

public

void set-classroomsint num!;

int get-classrooms!;

void set-officesint num!;

int get-offices!;

*;

void buildingset roomsint num!

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g - !

" rooms num; *

void buildingset-floorsint num!

" floors num; *

void buildingset-areaint num!

" area num; *

int buildingget-rooms!" return rooms; *

int buildingget-floors!

" return floors; *

int buildingget-area!

" return area; *

void houseset-bedroomsint num!

" bedrooms num; *

void houseset-bathsint num!

"baths num; *

int houseget-bedrooms!

" return bedrooms; *

int houseget-baths!

" return baths; *void schoolset-classroomsint num!

" classrooms num; *

void schoolset-officesint num!

" offices num; *

int schoolget-classrooms!

" return classrooms; *

int schoolget-offices!" return offices; *

int main!

"

house h;

school s;

h.set-rooms$!; h.set-floors0!;

h.set-area12%%!;

h.set-bedrooms2!;

h.set-baths0!;

cout

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Constructori$Jestructori

initiali&are automata

obiectele nu sunt statice

constructor: functie speciala, numele clasei

constructorii nu pot intoarce 'alori #nu au

tip de intoarcere%

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// +sing a constructor and destructor. void stac6pushint i!"

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#include

using namespace std;

#define 849: $%%

// 5his creates the class stac6.

class stac6 " int stc67849:;

int tos;

public

stac6!; // constructor

stac6!; // destructor

void pushint i!;

int pop!;

*;

// stac6s constructor

stac6stac6!

"

tos %; cout

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Clasele in C//

cu (class)

obiectele instantia&a clase

similare cu structNuri si unionNuri au functii

specificatorii de acces: public, pri'ate, protected

default: pri'ate protected: pentru mostenire, 'orbim mai tar&iu

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class nume_clasa {

private variabile si functii membru

specificator_de_acces:

variabile si functii membruspecificator_de_acces:

variabile si functii membru

$$ +++

specificator_de_acces:

variabile si functii membru

} lista_obiecte;

putem trece de la public la pri'ate si iar la public, etc+

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se foloseste mai mult a doua 'arianta un membru #neNstatic% al clasei nu poate

a'ea initiali&are

nu putem a'ea ca membri obiecte de tipulclasei #putem a'ea pointeri la tipul clasei%

nu auto, e*tern, register

class employee "

char name73%; // private by default

public

void putnamechar Bn!; // these are public

void getnamechar Bn!;

private double wage; // now, private again

public

void putwagedouble w!; // bac6 to public

double getwage!;

*;

class employee "

char name73%;

double wage;

public

void putnamechar Bn!;

void getnamechar Bn!; void putwagedouble w!;

double getwage!;

*;