Fundamentele Programarii CURS 1

8/15/2019 Fundamentele Programarii CURS 1

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Fundamentals of Programming

Guiding teachers

Lect. PhD CZIBULA Istvan

Assist. PhD GACEANU Radu

Assist. PhD MOLNAR Arthur

Assist. PhD MIHOC Tudr

PhD student BOCICOR Maria!Iu"iana

PhD student MARIAN Zsu#sanna

ScheduleLectures: 2 hours/week

Seminars: 2 hours/week

Labs: 2 hours/week

Course URL

Course page: http://cs.ubbcluj.ro/~istvanc/fp

E$ai"% [email protected]

Please use your ubbcluj.ro email.

Do not send emails from other accounts (yahoogmail etc!

http://cs.ubbcluj.ro/~istvanc/fp

mailto:[email protected]

mailto:[email protected]

http://cs.ubbcluj.ro/~istvanc/fp



"ims of the activity

• To know the key concepts of programming

•

To know the basic concepts of software engineering (design, implementation andmaintenance of software systems)

• To understand the basic software tools

• To learn Python programming language, and to get used to Python programming,

running, testing, and debugging programs

• To ac!uire and impro"e programming style



#ourse content

# $ntroduction to software de"elopment processes

2 Procedural programming

% &odular programming' ser defined types *b+ect based programming

-e"elopment principles . ayered architecture

0 -e"elopment principles . & -iagrams

1 Program testing and inspection

3ecursion

4 5lgorithms comple6ity

#7 -i"ision method

## 8acktracking method

#2 9earch algorithms and their comple6ity

#% 9ort algorithms and their comple6ity

#' *"er"iew



"ctivity and grading

ab (%7) ab documentations and programms

T (%7) Practical test (in the regular session)

; ('7) <ritten e6am (in the regular session)

9 7 7 9eminar acti"ity

Attendance is compulsory to all the activities

The exam is conditioned by minimum presence !"# Course



Lecture $% &ntroduction to development processes

• <hat is programming

• 8asic elements of a Python program

• 5 simple featuredri"en de"elopment process



'hat is programming

(ard)are and soft)are(ard)are computers (desktop, mobile, etc) and related devices

Soft)are programs or systems which run on hardware

Programming language notation that defines synta6 and semantics of programs

Python: a high le"el programming language =#> $t is a great language for beginner

programmers =%>

Python interpreter : a program which allow us to run/interpret new programs

Python standard library: builtin functions and types =2>

Program # ?ello world

print (@?ello worldA)



'hat computers do

B storage and retrie"al

internal memory

hard disk, memory stick

B operations

processor

B communication

keyboard, mouse, display

network connector

&nformation and data

*ata collection of symbols stored in a computer (eg #2% decimal number or @abcA string are

stored using binary representations)

&nformation interpretation of data for human purposes (eg #2%, @abcA)

&nformation and data processing

B $nput de"ices produce data from information (eg #2% taken from keyboard)

B -ata is stored in memory (eg binary representation of #2%)

B *utput de"ices produce information from data (eg #2% displayed from a binary

representation)

+asic operations of processors

B binary representation

B operations on binary representations (and, or, notD add, etc)



+asic elements of a Python program

Program 2 5dding two integers

E 3eads two integers and prints the sum of thema F input(G;nter the first number: G)b F input(G;nter the second number: G)c F int(a) H int(b)print(GThe sum of G, a, G H G, b, G is G, c)

Lexical elements

5 Python program is di"ided into a number of lines

Comments start with a hash (E) character and ends at the end of the line

&dentifiers (or names) are se!uences of characters which start with a letter (aI, 5J) or an

underscore (K) followed by Iero or more letters, underscores, and digits (74)Literals are notations for constant "alues of some builtin types

*ata model

All data in Python programs is represented by ob+ects, an ob,ect being Lthe PythonAs

abstraction for dataM

5n ob,ect has:

B an identity we may think of of it as the ob+ectAs address in memoryD

B a type which determines the operations that the ob+ect supports and also

defines the possible "aluesD

B a value*nce an ob+ect has been created, its identity and type cannot be changed

The "alue of some ob+ects can change *b+ects whose "alues can change mutable ob,ects

*b+ects whose "alues cannot be changed immutable ob,ects



Standard types

Types classifies "alues 5 type denotes a domain (a set of "alues) and operations on those

"alues

-umbers Numbers are immutable once created, their "alues cannot be changed

int (integers):

B 3epresents the mathematical set of integers (positi"e and negati"e, unlimited

precision)

B *perations: H, , O, /, see =2, section ''>

B iterals: #

bool (booleans):

B 3epresents the the truth "alues True and alse

B *perations: =2, section '#>

B iterals: alse, TrueD 7, #

float (reals):B 3epresents the mathematical set of double precision floating point numbers

B *perations: H, , O, /, see =2, section ''>

B iterals: %#'

Se.uences

B 3epresents the finite ordered sets inde6ed by nonnegati"e numbers

B et a be a se!uence

len(a) returns the number of itemsD

a=7>, a=#>, Q, a=len(a)#> represent the set of items

B ;6amples: =#, @aA>

Strings:

B 5 string is an immutable se!uenceD

B The items of a string are nicode characters

B iterals: @abcA, LabcM



/ariables

B Rariables are reser"ed memory locations to store "alues

B 5 variable has a name which refers to an ob+ectD so a "ariable has also a type,

and a "alue

B 5 "ariable is introduced in a program using a name binding operation

assignment

0xpressions

5n expression is a combination of e6plicit values, constants, "ariables, operators, and

functions that are interpreted according to the particular rules of precedence, which computes

and then produces/returns another "alue

;6amples:

B numeric e6pression: # H 2

B boolean e6pression # S 2

B string e6pression: @#A H @2A



Statements

9tatements are the basic operations of a program 5 program is a se!uence of statements

AssignmentB 5ssignment is a statement

B 5ssignments are used to (re)bind names to "alues and to modify items of

mutable ob+ects

B 8ind name:

6 F # E6 is a "ariable (of type int)

B 3ebind name:

6 F 6 H 2 Ea new "alue is assigned to 6

B 3ebind name of mutable se!uences:

y F =#, 2> Emutable se!uence

y=7> F # Ethe first item is bound to #

B +loc1

B 5 block is a piece of Python program te6t that is e6ecuted as a unit

B 5 se!uence of statements is a block

B 8locks of code are denoted by line indentation



(o) to )rite programs

+asic roles in soft)are engineering

Programmers2*evelopers

B se computers to write/develop programs for users

Clients2sta1eholders

B <ho is affected by the outcome of a pro+ect

Users

● Run programs on their computers.

5 soft)are development process is an approach to building, deploying, and possible

maintaining software $t indicates:

B <hat tasks/steps can be taken during de"elopment

B $n which order

<e will use: a simple featuredri"en de"elopment process



Problem statement 5 problem statement is a short description of the problem being sol"ed

Calculator Problem statement

5 teacher (client) needs a program for students (users) who learn or use rational numbers

The program shall help students to make basic arithmetic operation

Re.uirementsRe.uirements define in details what is needed from the client perspecti"e 3e!uirements

define:

B <hat the clients needD andB <hat the system must include to satisfy the clientU needs

Re.uirements guidelines

B 3ood re.uirements ensure your system )or1s li1e your customers expect%

4*on5t create problems to solve problems67

B Capture the list of features your software is supposed to do

B The list of features must clarify the problem statement ambiguities

B



Feature

Feature is a small, client"alued function:

B e6pressed in the form 8action9 <result> Sob+ectV,

action a function that the application must pro"ide

result the result obtained after e6ecuting the function

ob+ect an entity within the application that implements the

function

B and typically can be implemented )ithin a fe) hours (in order to be easy to

make estimates)

Calculator eature list

# Add a number to calculator

2 Clear calculator

% Undo the last operation (user may repeat this operation)



A simple feature:driven development process

B 8uild a feature list from the problem statement

B Plan iterations (at this stage, an iteration may include asingle feature)

B or each iteration

&odel planned features

$mplement and test features

5n iteration is a set period of time within a pro+ect in which you produce a stable, e6ecutable

"ersion of the product, together with any other supporting documentation

&teration will result in a working and usefoul program for the client (will interact with the

user, perform some computation, show results)

;6ample: iteration plan

&teration Planned features

$# # Add a number to calculator

$2 2 Clear calculator

$% % Undo the last operation (user may repeat this operation)



&teration modeling 5t the beginning of each iteration you must understand the work re!uired to implement it Wou

must investigate2analy;e each feature in order to determine work items/tasks Then, work

items are scheduled ;ach work item will be independently implemented and tested

&teration $ : Add a number to calculator or simple programs (eg Calculator), running scenarios help de"eloper to understand what

must be implemented 5 running scenario shows possible interactions between users and the

program under de"elopment

Running scenario for adding numbers

ser Program -escription

a 7 9hows total

b #/2 5dd number to calculator

c #/2 9hows total

d 2/% 5dd number to calculator

e /0 9hows total

f #/0 5dd number to calculator

g # 9hows total

h 0/0 5dd number to calculator

i 7 9hows total



'or1 items2tas1s

3uidelines for tas1s

B -efine a task for each operation not already pro"ided by the platform (Python),

eg T#, T2

B -efine a task for implementing the interaction between ser and Program (ser

$nterface), eg T'

B -efine a task for implementing all operations re!uired by $, eg T%

B -etermine dependencies between tasks (eg T' V T% V T2 VT#, where V

means depends on)

B 9chedule items based on the dependencies between them

bottom up: schedule first task without dependencies, or with

dependencies scheduled before

T# Compute the greatest common di"isor of two integers (see g, i)

T2 5dd two rational numbers (see c, e, g, i)

T% $mplement calculator: init, add, and total

T' $mplement user interface



Tas1 $% Compute gcd

Test case

5 test case specifies a set of test inputs, e6ecution conditions, and e6pected results that you

identify to e"aluate a particular part of a program

$nput params: a, b gcd (a, b): c, where c is the greatest common di"isor of a and b

2 % #

2 ' 2

0 ' 2

7 2 2

2 7 2

2' 4 %

2 7 Ralue;rror

7 2 Ralue;rror



&f statement

The if statement is used for conditional e6ecution

gcd if statement and tests

def gcd(a, b): GGG 3eturn the greatest common di"isor of two positi"e integers 3aise Ralue;rror if the parameters are negati"e integers GGG if a FF 7: return b else: if b FF 7: return a

def testKgcd(): assert gcd(7, 2) FF 2 assert gcd(2, 7) FF 2 testKgcd()



'hile statement

The while statement is used for repeated e6ecution as long as an e6pression is true

gcd while statement and tests

def gcd(a, b): GGG 3eturn the greatest common di"isor of twopositi"e integers -oc test e6amples: GGG if a FF 7: return b else: if b FF 7:

return a else: while a XF b: if a V b: a F a b else: b F b a return a

def testKgcd(): assert gcd(7, 2) FF 2 assert gcd(2, 7) FF 2 assert gcd(2, %) FF # assert gcd(2, ') FF 2 assert gcd(0, ') FF 2 assert gcd(2', 4) FF %

testKgcd(



References# The Python language reference http :// docs python org /py % k /reference /inde6 html

2 The Python standard library http :// docs python org /py % k /library /inde6 html % The Python tutorial http :// docs python org /tutorial /inde6 html

http://docs.python.org/py3k/reference/index.html



http://docs.python.org/py3k/library/index.html



http://docs.python.org/tutorial/index.html




















































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Fundamentele Programarii CURS 1