CS11001/CS11002ProgrammingandDataStructures

(PDS)(Theory:3-0-0)

Teacher:SourangshuBha@acharyasourangshu@gmail.com

h@p://cse.iitkgp.ac.in/~sourangshu/

DepartmentofComputerScienceandEngineeringIndianInsJtuteofTechnologyKharagpur

TentaJveSyllabusIntroducJontodigitalcomputersBasicprogrammingconstructs

VariablesandsimpledatatypesAssignmentsInput/outputCondi7onsandbranchingLoopsanditera7onItera7vesearchingandsor7ngalgorithmsProgrammingExamples:Sor7ng…etc

Advancedprogrammingconstructs

Func7onsandrecursionRecursivesor7ngalgorithmsArraysandstrings StructuresPointersanddynamicmemoryalloca7on

FileHandling

TentaJveSyllabus

PerformanceanalysisofprogramsDatastructures

AbstractdatatypesOrderedlistsStacksandqueues

ProgrammingLanguage:C

CourseMaterials

Donotusebookswri@enonspecificCcompilerslikeTurboC,gccUseanystandardtextbookonANSICSomeusefultextbooks:ü  BrianW.KernighanandDennisM.Ritchie

TheCProgrammingLanguage,Pren7ceHallofIndia.ü  E.Balaguruswamy

ProgramminginANSIC,TataMcGraw-Hillü  ByronGoTried

Schaum’sOutlineofProgrammingwithC,McGraw-Hillü  SeymourLipschutz,

DataStructures,Schaum’sOutlineSeries,TataMcGraw-Hillü  EllisHorowitz,SatrajSahniandSusanAnderson-Freed,

FundamentalsofDataStrcuturesinC,W.H.FreemnandCompany

CourseMaterials

Webreferences:

hWp://cse.iitkgp.ac.in/~pds/

SomeusefulsoYware:hWp://cse.iitkgp.ac.in/~pds/soYware/

Notes:

hWp://cse.iitkgp.ac.in/~pds/notes/

Courserelatedinforma7onandannouncements:hWp://cse.iitkgp.ac.in/~pds/current/

A@endanceintheclassesisMANDATORY

StudentshavingpooraWendancewillbepenalizedintermsofthefinalgrade/deregistra7on.

ProxyintheaWendancewillbeheavilypenalized.Eachproxyin

theclasswillresultinthededuc7onof5marksfromtotalmarksyouobtained.

ItisyourresponsibilitytochecknosuchaWendancemarked

againstyou.

CourseFactsforsecJon1,2,3

Ø SecJons:1,2,3Ø ClassRoom:V2

Ø TimeSchedule:Monday8:00–09:55am,Wednesday12:00–12:55pm

Ø ClassTeacher:SudeshnaSarkar

Ø TeachingAssistant(TA):AbhijitMondal

AnandaDasMadhumitaMallickSaptarshiMisra

CourseFactsforsecJons4,5Ø SecJons:4,5Ø ClassRoom:NR121

Ø TimeSchedule:Wednesday12:00–12:55pm,Thursday11:00–11:55,Friday9:00–09:55

Ø ClassTeacher:DebasisSamanta

Ø TeachingAssistant(TA):CheemaBaljeetSingh

SreejaSRAnushriSahaAnoopA

CourseFactsforsecJons6,7Ø SecJons:6,7Ø ClassRoom:NR222

Ø TimeSchedule:Monday(10:00-10:55);Wednesday(9:00-9:55);Thursday(10:00-10:55)

Ø ClassTeacher:SourangshuBhaWacharya

Ø TeachingAssistant(TA):RijulaKar,

AbirDey,SangaChaki,SankarshanMridha

CourseFactsDistribuJonofMarks:

ClassTest1: 10MidSemesterExam: 30ClassTest2: 10EndSemesterExam: 50

ImportantDates:

ClassTest1:Thursday,February2,2017,7:00-8:00pmClassTest2: WednesdayMarch15,20177:00-8:00pmMid-Semester: February12-21,2017(asperins7tuteschedule)End-Semester: April20–April28,2017(asperins7tuteschedule)

TentaJvesyllabusoftests:

CT1syllabus: Un7lArraysandStringsMidSem: Un7lFunc7ons,includingrecursionCT2: Un7lArrays(2D)EndSem: Everything

Let us see

WhatisaComputer?

Central Processing

Unit (CPU)‏

Input Device

Output Device

Main Memory

Storage (Hard disk)

It is a machine which can accept data, process them, and output results.

The Box

CentralProcessingUnit(CPU)

– Allcomputa7onstakeplacehereinorderforthecomputertoperformadesignatedtask.

–  Ithasalargenumberofregisterswhichtemporarilystoredataandprograms(instruc7ons).

–  Ithascircuitrytocarryoutarithme7candlogicopera7ons,takedecisions,etc.

–  Itretrievesinstruc7onsfromthememory,interprets(decodes)them,andperformtherequestedopera7on.

while<powerison>1.fetchtheinstruc@on <decodeit>2.executetheinstruc@on

• Usessemiconductortechnology• Allowsdirectaccess• RAM–RandomAccessMemory

– Somemeasurestoberemembered• 1K=210(=1024)‏• 1M=220(=onemillionapprox.)‏• 1G=230(=onebillionapprox.)‏

MainMemory

InputOutput(I/O)•  InputDevice

–  Keyboard,Mouse,Scanner,DigitalCamera•  OutputDevice

– Monitor,Printer•  StoragePeripherals

– Magne7cDisks:harddisk,floppydisk•  Allowsdirectaccess

– Op7calDisks:CDROM,CD-RW,DVD•  Allowsdirectaccess

–  FlashMemory:pendrives•  Allowsdirectaccess

– Magne7cTape:DAT•  Onlysequen7alaccess

TypicalConfiguraJonofaPC

•  CPU: Intel(R)Core(TM) i5-4570CPU,3.2GHz

•  MainMemory: 4GB•  HardDisk: 500GB•  FloppyDisk: Notpresent•  CDROM: DVDRWcombo-drive•  InputDevice: Keyboard,Mouse•  OutputDevice: Monitor•  Ports: USB,Firewire,Infrared

NumberSystem•  Decimalnumbersystem

–  Tendigits:0,1,2,3,4,5,6,7,8,9–  Everydigitposi7onhasaweight:powerof10.

•  Example:234 =2x102+3x101+4x100

250.67=2x102+5x101+0x100 +6x10-1+7x10-2

Numbersystemindigitalcomputer

•  Adigitalcomputerisbuiltoutof7nyelectronicswitches.–  Fromtheviewpointofeaseofmanufacturingandreliability,suchswitchescanbeinoneoftwostates,ONorOFF.

–  Thiscanberepresentedby0(OFF)and1(ON).

•  Thissuggestsforabinarynumbersystemforadigitalcomputer.

ConceptofBitsandBytes•  Bit

– Asinglebinarydigit(0or1).•  Nibble

– Acollec7onoffourbits(say,0110).•  Byte

– Acollec7onofeightbits(say,01000111).•  Kilobyte(KB),MB,GB

–  ?????•  Word

– Dependsonthecomputer.–  Typically4or8bytes(thatis,32or64bits).

DecimalandBinary

•  Ak-bitdecimalnumber–  Canexpressunsignedintegersintherange0to10k–1

•  Fork=3,from0to999.

•  Ak-bitbinarynumber–  Canexpressunsignedintegersintherange0to2k–1

•  Fork=8,from0to255.•  Fork=10,from0to1023.

ComputerLanguages

•  MachineLevelLanguage(MLL)– Expressedinbinary.– Directlyunderstoodbythecomputer.– Notportable;variesfromonemachinetypetoanother.

•  ProgramwriWenforonetypeofmachinewillnotrunonanothertypeofmachine.

– Difficulttouseinwri7ngprograms.

Example:MachineLevelLanguage

Binary Hexadecimal

ComputerLanguages•  AssemblyLevelLanguage(ALL)

– Mnemonicformofmachinelanguage.– Easiertouseascomparedtomachinelanguage.

•  Forexample,use“ADD”insteadof“10110100”.

– Notportable(likemachinelanguage).– Requiresatranslatorprogramcalledassembler.

Assembler Assembly language program

Machine language program

Example:AssemblyLevelLanguage

•  Assemblylanguageisalsodifficulttouseinwri7ngprograms.– Requiresmanyinstruc7onstosolveaproblem.

•  Example:Findtheaverageofthreenumbers.MOV A,X ; A = X ADD A,Y ; A = A + Y

ADD A,Z ; A = A + Z DIV A,3 ; A = A / 3

MOV RES,A ; RES = A

RES = (X + Y + Z) / 3

High-LevelLanguage•  Machinelanguageandassemblylanguagearecalledlow-levellanguages.–  Theyareclosertothemachine.– Difficulttouse.

•  High-levellanguagesareeasiertouse.–  Theyareclosertotheprogrammer.–  Examples:

•  Fortran,Cobol,C,C++,Java.–  Requiresanelaborateprocessoftransla7on.

•  UsingasoYwarecalledcompiler.–  Theyareportableacrossplavorms.

Example:HighLevelLanguage

•  Example:Findtheaverageofthreenumbers.

RES = (X + Y + Z) / 3

TherelaJonship

HighLevelLanguage

AssemblyLevelLanguage

MachineLevelLanguage

Assembler

Compiler

ClassificaJonofSoeware

1.  Applica7onSoYware•  Usedtosolveapar7cularproblem.•  Editor,financialaccoun7ng,weatherforecas7ng,etc.

2.  SystemSoYware•  Helpsinrunningotherprograms.•  Compiler,opera7ngsystem,etc.

OperaJngSystems

•  A system soYware to interface between computerhardware and soYware resources includingapplica7onprograms.

•  Categoriesofopera7ngsystems:– Singleuser– Mul7user

•  Timesharing•  Mul7tasking•  Real7me

OperaJngSystems•  Popularopera7ngsystems:

– DOS: single-user– Windows: single-usermul7tasking– Unix: mul7-user– Linux: afreeversionofUnix

•  ThelaboratoryclasswillbebasedonUnix.

Programming in C

UniversalstarJngpoint

#include <stdio.h> int main() { printf (“Hello World\n”); return 0;

}

Header file includes functions for input/output

Main function is executed when you run the program. (Later we will see how to pass its parameters)

Curly braces within which statements are executed one after another.

Statement for printing the sentence within double quotes (“..”). ‘\n’ denotes end of line.

Returnvaluetofunc7on

1.   Writeaprogramandsaveit.2.   Compiletheprogramusingthecorrectcompiler.3.   Executetheprogram

Threestepstofollow

1.vihello.c#include<stdio.h>intmain(){prini("HelloWorld\n");return0;}2.$cchello.c$3.$./a.outHelloWorld

IntroducJontoC•  Cisageneral-purpose,structuredprogramminglanguage.

–  Resemblesotherhigh-levelstructuredprogramminglanguages,suchasPascalandFortran-77.

–  Alsocontainsaddi7onalfeatureswhichallowittobeusedatalowerlevel.

•  Ccanbeusedforapplica7onsprogrammingaswellasforsystemsprogramming.

•  Thereareonly32keywordsanditsstrengthliesinitsbuilt-infunc7ons.

•  Cishighlyportable,sinceitrelegatedmuchcomputer-dependentfeaturestoitslibraryfunc7ons.

HistoryofC•  Originallydevelopedinthe1970’sbyDennisRitchieatAT&TBellLaboratories.–  OutgrowthoftwoearlierlanguagesBCPLandB.

•  Popularitybecamewidespreadbythemid1980’s,withtheavailabilityofcompilersforvariousplavorms.

•  Standardiza7onhasbeencarriedouttomakethevariousCimplementa7onscompa7ble.–  AmericanNa7onalStandardsIns7tute(ANSI)

StructureofaCprogram•  EveryCprogramconsistsofoneormorefunc7ons.

–  Oneofthefunc7onsmustbecalledmain.

–  Theprogramwillalwaysbeginbyexecu7ngthemainfunc7on.

•  Eachfunc7onmustcontain:–  Afunc7onheading,whichconsistsofthefunc@onname,followedbyanop7onallistofargumentsenclosedinparentheses.

–  Alistofargumentdeclara@ons.

–  Acompoundstatement,whichcomprisestheremainderofthefunc7on.

StructureofaCprogram

•  Eachcompoundstatementisenclosedwithinapairofbraces:‘{‘and‘}’–  Thebracesmaycontaincombina7onsofelementarystatementsandothercompoundstatements.

•  Commentsmayappearanywhereinaprogram,enclosedwithindelimiters‘/*’and‘*/’.–  Example:

a=b+c;/*ADDTWONUMBERS*/

#include <stdio.h> int main() {

int n; scanf(“%d”,&n); printf(“%d”,n); return 0;

}

InandOutonly#include <stdio.h> int main() {

int n; scanf(“%d”,&n); printf(“%d”,n+n); return 0;

}

#include <stdio.h> int main() {

int n,m; scanf(“%d”,&n);/* Read the value of n */ m=n+n; printf(“%d”,m); return 0;

}

InandOutonly

#include <stdio.h> int main() {

int n,m; scanf(“%d”,&n);/* Read the value of n */ m=n+n; printf(“%d”,m); return 0;

}

Control character for printing value of m in decimal digits.

Integers variables declared before their usage.

Comments within /* .. */

Input statement for reading variable from the keyboard

#include <stdio.h> #define PI 3.1416 double area_of_circle(float); double area_of_circle (float radius) {

return PI*radius*radius; } int main() {

int squareSide; double area; scanf(“%d”, &squareSide); area= area_of_circle(squareSide/2); printf(“Area of the circle enclosing the square of side %d

is: %f\n”, squareSide, area); return 0;

}

AcompleteCprogramIncludeheaderfiles

Declareglobalvariables,constantsandfunc7on

prototypes

Func7onbodies

Theremustbeamainfunc7oninanyCprogram.

#include <stdio.h> #define PI 3.1416 double area_of_circle(float); double area_of_circle (float radius) {

return PI*radius*radius; } int main() {

int squareSide; double area; scanf(“%d”, &squareSide); area= area_of_circle(squareSide/2); printf(“Area of the circle enclosing the square of side %d

is: %f\n”, squareSide, area); return 0;

}

AcompleteCprogramPreprocessor statement. Replace PI by 3.1416 before compilation.

Function called

Example of a function called as per need from main program.

main()funcJon:startofexecuJon

TheCCharacterSet

•  TheClanguagealphabet:–  UppercaseleWers‘A’to‘Z’–  LowercaseleWers‘a’to‘z’–  Digits‘0’to‘9’–  Certainspecialcharacters:

! # % ^ & * ( )

-  _ + = ~ [ ] \

| ; : ‘ “ { } ,

. < > / ? blank

IdenJfiers•  Iden7fiers

–  Namesgiventovariousprogramelements(variables,constants,func7ons,etc.)

– MayconsistofleIers,digitsandtheunderscore(‘_’)character,withnospacebetween.

–  FirstcharactermustbealeWer.

–  Aniden7fiercanbearbitrarylong.•  SomeCcompilersrecognizeonlythefirstfewcharactersofthename(16or31).

–  Casesensi7ve•  ‘area’,‘AREA’and‘Area’arealldifferent.

Keywords•  Keywords

–  Reservedwordsthathavestandard,predefinedmeaningsinC.

–  Cannotbeusedasiden7fiers.

–  OKwithincomments.

–  StandardCkeywords:

auto break case char const continue default do

double else enum extern float for goto if

int long register return short signed sizeof static

struct switch typedef union unsigned void volatile while

ValidandInvalidIdenJfiers•  ValididenJfiers

Xabcsimple_interesta123LISTstud_nameEmpl_1Empl_2avg_empl_salary

•  InvalididenJfiers10abc“hello”simpleinterest(area)%rate

int::integerquan7tyTypicallyoccupies4bytes(32bits)inmemory.

char::singlecharacterTypicallyoccupies1byte(8bits)inmemory.

float::floa7ng-pointnumber(anumberwithadecimalpoint)Typicallyoccupies4bytes(32bits)inmemory.

double::double-precisionfloa7ng-pointnumber

BasicDataTypesinC

Precisionreferstothenumberofsignificantdigitsa6erthedecimalpoint.

AugmentedDataType

•  Someofthebasicdatatypescanbeaugmentedbyusingcertaindatatypequalifiers:–  short–  long–  signed–  unsigned

•  Typicalexamples:–  shortint–  longint–  unsignedint

Integertype

Type Storagesize(inbyte) Valuerange

char 1 -128to127or0to255unsignedchar 1 0to255signedchar 1 -128to127

int 2or4 -32,768to32,767or-2,147,483,648to2,147,483,647

unsignedint 2or4 0to65,535or0to4,294,967,295short 2 -32,768to32,767unsignedshort 2 0to65,535

long 4 -2,147,483,648to2,147,483,647unsignedlong 4 0to4,294,967,295

Integertype

unsignedcharè1byteè8bits è00000000to11111111è0to255

11111111è1×27+1×26+1×25+1×24+1×23+1×22+1×21+1×20

signedcharè1byteè8bits è00000000to11111111è-128to127

1111111è1×26+1×25+1×24+1×23+1×22+1×21+1×20

FloaJng-pointtype

Type Storagesize(inbyte) Valuerange Precision

float 4 1.2E-38to3.4E+38 6decimalplacesdouble 8 2.3E-308to1.7E+308 15decimalplaceslongdouble 10 3.4E-4932to1.1E+4932 19decimalplaces

E or e means “10 to the power of”

ASCIITable

ExtendedASCIITable(AmericanStandardCodeforInforma7onInterchange)

SomeExamplesofDataTypes

•  int0,25,-156,12345,-99820

•  char‘a’,‘A’,‘*’,‘/’,‘’

•  float23.54,-0.00345,25.02.5E12,1.234e-5

E or e means “10 to the power of”

Constants

Constants

Numeric Constants

Character Constants

string single character

floating-point integer

IntegerConstants

•  Consistsofasequenceofdigits,withpossiblyaplusoraminussignbeforeit.–  Embeddedspaces,commasandnon-digitcharactersarenotpermiWedbetweendigits.

•  Maximumandminimumvalues(for32-bitrepresenta7ons)Maximum::2147483647Minimum::–2147483648

FloaJng-pointConstants•  Cancontainfrac7onalparts.

•  Verylargeorverysmallnumberscanberepresented.23000000canberepresentedas2.3e7

•  Twodifferentnota7ons:1.  Decimalnota7on

25.0,0.0034,.84,-2.2342.  Exponen7al(scien7fic)nota7on

3.45e23,0.123e-12,123E2 e means “10 to the power of”

SingleCharacterConstants

•  Containsasinglecharacterenclosedwithinapairofsinglequotemarks(‘’).–  Examples::‘2’,‘+’,‘Z’

•  Somespecialbackslashcharacters‘\n’ newline‘\t’ horizontaltab‘\’’ singlequote‘\”’ doublequote‘\\’ backslash‘\0’ null

StringConstants

•  Sequenceofcharactersenclosedindoublequotes(““).–  ThecharactersmaybeleWers,numbers,specialcharactersandblankspaces.

•  Examples:“nice”,“GoodMorning”,“3+6”,“3”,“C”

•  Differencesfromcharacterconstants:–  ‘C’and“C”arenotequivalent.–  ‘C’hasanequivalentintegervaluewhile“C”doesnot.

Variables

•  Itisadatanamethatcanbeusedtostoreadatavalue.

•  Unlikeconstants,avariablemaytakedifferentvaluesinmemoryduringexecu7on.

•  Variablenamesfollowthenamingconven7onforiden7fiers.– Examples::temp,speed,name2,current

Example int a, b, c; char x; a = 3; b = 50; c = a – b; x = ‘d’; b = 20; a = a + 1; x = ‘G’;

Variables

Constants

DeclaraJonofVariables

•  Therearetwopurposes:1.  Ittellsthecompilerwhatthevariablenameis.2.  Itspecifieswhattypeofdatathevariablewillhold.

•  Generalsyntax:data-typevariable-list;

•  Examples:intvelocity,distance;inta,b,c,d;floattemp;charflag,op7on;

AddressandContent

1349

1350

1351

1352

speed

11101010

int speed;

speed=234;

speed 234 &speed 1350

Binaryof234

Everyvariablehasanaddress(inmemory),anditscontents.

AddressandContent

•  InCterminology,inanexpressionspeedreferstothecontentsofthememoryloca7on.

&speedreferstotheaddressofthememoryloca7on.

•  Examples:printf (“%f %f %f”, speed, time, distance); scanf (“%f %f”, &speed, &time);

AnExample

#include <stdio.h> int main() { float speed, time, distance; scanf (“%f %f”, &speed, &time); distance = speed * time; printf (“\n The distance traversed is: \n”, distance); return 0; }

Address of speed

Content of speed

AssignmentStatement

•  Usedtoassignvaluestovariables,usingtheassignmentoperator(=).

•  Generalsyntax:variable_name = expression;

•  Examples:velocity = 20; b = 15; temp = 12.5; A = A + 10; v = u + f * t; s = u * t + 0.5 * f * t * t;

AdvancedAssignmentStatement

•  Assignmentduringdeclara7onint speed = 30; char flag = ‘y’;

•  Mul7plevariableassignmenta = b = c = 5; flag1 = flag2 = ‘y’;

speed = flow = 20.0;

OperatorsinExpressions

Operators

Arithmetic Operators

Relational Operators

Logical Operators

ArithmeJcOperators

•  Addi7on::+•  Subtrac7on::–•  Division:: /•  Mul7plica7on::*•  Modulus:: %

X + Y 48

X – Y 2

X * Y 575

X / Y ?

X % Y ??

X=25; Y=23;

OperatorPrecedence

•  Indecreasingorderofpriority1.  Parentheses::()2.  Unaryminus::–53.  Mul7plica7on,Division,andModulus4.  Addi7onandSubtrac7on

•  Foroperatorsofthesamepriority,evalua7onisfromleYtorightastheyappear.

•  Parenthesismaybeusedtochangetheprecedenceofoperatorevalua7on.

Examples:ArithmeJcexpressions

v = u + f * t; è X = x * y / z è A = a + b – c * d / e èA = -b * c + d % e è

Examples:ArithmeJcexpressions

v = u + f * t; è v=u+(f*t);X = x * y / z è X=(x*y)/zA = a + b – c * d / e èA=((a+b)-((c*d)/e))A = -b * c + d % e èA=(((-b)*c)+(d%e))

IntegerArithmeJc

•  Whentheoperandsinanarithme7cexpressionareintegers,theexpressioniscalledintegerexpression,andtheopera7oniscalledintegerarithme@c.

•  Integerarithme7calwaysyieldsintegervalues.

RealArithmeJc

•  Involvingonlyrealorfloa7ng-pointoperands(includingdouble,longdouble).

•  Sincefloa7ng-pointvaluesareroundedtothenumberofsignificantdigitspermissible,thefinalvalueisanapproxima7onofthefinalresult. A=22/7*7*7=(((22/7)*7)*7)=153.86 =(((22*7)/7)*7)=154

•  Themodulusoperatorcannotbeusedwithrealoperands.

ArithmeJc–integer/real

•  AnexpressioncontainsonlyintegeroperandsèIntegerarithme7cwillbeperformed.

•  AnexpressioncontainsonlyrealoperandsèRealarithme7cwillbeperformed.

•  AnexpressioncontainsintegerandrealboththeoperandsèRealarithme7cwillbeperformed.

TypecasJng

•  Afaultyreciprocalfinder

#include <stdio.h> int main () { int n; scanf("%d",&n); printf("%d\n",1/n); return 0;

}

Thedivision1/nisofintegers(quo7ent).Theformat%disforprin7ngintegers.

TypecasJng

#include <stdio.h>

int main () {

int n;

scanf("%d",&n);

printf("%f\n",1.0/n);

return 0; }

#include <stdio.h>

int main () {

int n;

float x;

scanf("%d",&n);

x=(float)1/n; printf("%f\n",x);

return 0;

}

TypecasJng

Integertorealint a=10; float b;

b=(float)a;

Realtointeger

int a; float b=3.14; a=(int)b;

Realtoreal float b; double c=3.14;

b=(float)c;

Realtoreal float b;

double c; c=22.0/7.0;

b=(float)c;