computer programming –i - strawberry -...

ComputerProgramming–I

DevelopedByStrawberry

CourseOutcome•  AWerSuccessfulcompleIonofthiscourse,studentswillbeableto–  Illustrateflowchartandalgorithmforagivenproblem

– DevelopandExecuteCprogramsusingbasicprogrammingconstructs.

–  ImplementCprogramsusingvariousdatatypesandfuncIons

–  SolveproblemsusingPointers

Algorithms&Flowchart

WhatisanAlgorithm?

•  ComputerScienIstNiklausWirthstatedthat– Program=Algorithms+Data

– Algorithm:Procedureforsolvingaprobleminfinitenumberofsteps.

ExampleforAlgorithm

•  Makingapotoftea:1.  IfthekeJledoesnotcontainwater,thenfillthe

keJle.2.  PlugthekeJleintothepowerpointandswitchiton.3.  Iftheteapotisnotempty,thenemptytheteapot.4.  Placetealeavesintheteapot.5.  IfthewaterinthekeJleisnotboiling,thengoto

step5.6.  SwitchoffthekeJle.7.  PourwaterfromthekeJleintotheteapot.

ExampleforAlgorithm•  Makingapotoftea:

1.  IfthekeJledoesnotcontainwater,thenfillthekeJle.(Decisionmaking)

2.  PlugthekeJleintothepowerpointandswitchiton.

3.  If the teapot is not empty, then empty theteapot.(Decisionmaking)

4.  Placetealeavesintheteapot.5.  If thewater in thekeJle isnotboiling, thengo

tostep5.(Repe::on)6.  SwitchoffthekeJle.7.  PourwaterfromthekeJleintotheteapot.DevelopedByStrawberry

AlgorithmFeatures

•  Sequence(alsoknownasprocess)•  Decision(alsoknownasselecIon)•  RepeIIon(alsoknownasiteraIonorlooping)

Sequence

•  Each step or process in the algorithm isexecutedinthespecifiedorder.

Thedecisionconstructs–if…then..else

•  Outcomeofadecision–eithertrueorfalse.–  IftodayisFridaythencollectpay.

•  It iseither true that ‘today is Friday’or it is false that‘todayisnotFriday’.

•  Itcannotbeboth.•  GeneralForm:IfProposiIonIfFridaythenprocess1thencollectpayelseelseprocess2callonnextMonday

RepeIIon•  RepeataprocessorsequenceofprocessunIlacondiIonbecomestrue.

•  GeneralForm:RepeatRepeatProcess1FillwaterinkeJleProcess2UnIlKeJleisfull……………..ProcessNUnIlProposiIon

RepeIIon-While•  WhathappensifthekeJleisalreadyfull?•  Whileloopmoreappropriate.WhileproposiIonWhilekeJleisnotfullbeginfillwaterinkeJle.Process1

RepeIIon–Ifthengoto1.  FillsomewaterinkeJle2.  IfkeJlenotfullthengoto1.

Variables1.  Program consists of algorithm (Process) and

data.2.  Dataneedstobestored.3.  Data is contained(stored) inwhat is calleda

‘variable’.4.  The variable is a container of a value that

may change during the execuIon of theprogram.

Variables1.  Eachvariableinaprogramisgivenaname2.  Example: Water_Level, Water_Temprature,

Num1,Num2Howtousevariableinalgorithm?IfWater_Levelis0thenfillthekeJle.

Rulesforalgorithm1.  Eachalgorithmwillbe logicallyenclosedby

twostatementsSTARTandSTOP.

2.  Toacceptdatafromuser,theINPUTorREADstatementsaretobeused.

3.  Todisplayanyusermessage,or thecontentinavariablePRINTstatementwillbeused.

Rulesforalgorithm–ArithmeIcOperators

1.  ‘ß’Assignmentoperator xß 6 means the value 6 is assigned to thevariablex.ZßX+Y(ValueofX+ValueofY)assignedtoZZßX-YXß5Yß6ZßX*YZßX/Y

Rulesforalgorithm–RelaIonalOperators1.  ‘>’greaterthan

X>Y means if thevaluecontained inX is larger thanthat inYthen outcome of the expression is true else outcome ofexpressionisfalse.‘<=‘LessthanorequaltoX<=Y means that if the value held in X is either less than orequal to thevalueheld inY thenoutcomeof theexpression istrueelsefalse.OtherrelaIonaloperators:>,>=,=,!=(Notequalto)

Rulesforalgorithm–Logicaloperators1.  ‘AND’conjuncIonTheoutcomeof theexpression is truewhenbothproposiIonsaretrueotherwiseitisfalse.Xß2Yß1X=2ANDY=0X=2truebutY=0isfalseSooutcomeoftotalexpressionisfalse.

Rulesforalgorithm–Logicaloperators2.  ‘OR’DisjuncIonThe outcome of an expression is true when anyone of theproposiIonsistrueelseitisfalse.Xß2Yß1X=2ORY=0X=2istruebutY=0isfalseBut as ‘OR’ is used as one proposiIon is true result for enIreexpressionwillbetrue.

AlgorithmExampleAlgorithmforfindingthesumofanytwonumbers.SoluIon:LetthetwonumbersbeAandBandlettheirsumbeequaltoC.Then,thedesiredalgorithmisgivenasfollows:1.  START2.  PRINT“ENTERTWONUMBERS”3.  INPUTA,B4.  CßA+B5.  PRINTc6.  STOP

AlgorithmExampleAlgorithm for determining the remainder of a division operaIonwherethedividendanddivisorarebothintegers.SoluIon: Let N and D be the dividend and divisor, respecIvely.Assume Q to be the quoIent, which is an integer, and R to be theremainder.Thealgorithmforthegivenproblemisasfollows:1.  START2.  PRINT“ENTERDIVIDEND”3.  INPUTN4.  PRINT“ENTERDIVISOR5.  INPUTD6.  QßN/D(INTEGERDIVISION)7.  RßN-Q*D8.  PRINTR9.  STOP

AlgorithmExampleConstructthealgorithmforinterchangingthenumericvaluesoftwovariables.Hint: If A and B are two variables with values 5 and 6respecIvely. Interchange values ofA andB, so that valueofAwillbecome6andvalueofBwillbecomeA.UsethirdvariableCforit.

AlgorithmExampleSoluIon: Let the two variablesbeA andB. ConsiderC tobe athird variable that is used to store the value of one of thevariablesduringtheprocessofinterchangingthevalues.Thealgorithmforthegivenproblemisasfollows:1.  START2.  PRINT“ENTERTHEVALUEOFA&B”3.  INPUTA,B4.  CßA5.  AßB6.  BßC7.  PRINTA,B8.  END

AlgorithmExampleWriteanalgorithmthatcomparestwonumbersandprintseitherthemessage idenIfying the greater number or themessage staIng thebothnumbersareequal.SoluIon:LetAandBbetwovariablestorepresentthetwonumbersthat are being compared. The algorithm for this problem is given asfollows:1.  START2.  PRINT“ENTERTWONUMBERS”3.  INPUTA,B4.  IFA>BTHEN

PRINT“AISGREATERTHANB”5.  IFB>ATHENPRINT“BISGREATERTHANA”6.  IFA=BTHENPRINT“BOTHAREEQUAL”7.STOP

AlgorithmExampleWriteanalgorithmprintthelargestnumberamongthreenumbers.SoluIon:LetthethreenumbersberepresentedbyA,BandC.SoluIonforthealgorithmisasfollows:

SoluIon11.  START2.  PRINT “ENTER THREE

NUMBERS”3.  INPUTA,B,C4.  IFA>=BANDB>=CTHENPRINTA5.  IFB>=CANDC>=ATHENPRINTB6.  ELSEPRINTC7.STOP

SoluIon21.  START2.  PRINT“ENTERTHREE

NUMBERS”3.  INPUTA,B,C4.  IFA>CTHENIFA>CTHENPRINTAELSEPRINTCELSEIFB>CTHENPRINTBELSEPRINTC5.STOPDevelopedByStrawberry

AlgorithmExampleTakethreesidesofatriangleasinputandcheckwhetherthetrianglecanbedrawnornot.Classifythetriangleasequilateral,isosceles,orscalene.SoluIon: Let the length of three sides of triangle be represented by A,B and C.SoluIonforthealgorithmisasfollows:

SoluIon11.  START2.  PRINT“ENTERLENGTHOFTHREESIDESOFATRAINGLE”3.  INPUTA,B,C4.  IFA+B>CANDB+C>AANDA+C>BTHENPRINT”TRAINGLECANBEDRAWN”ELSEPRINT“TRIANBLECANNOTBEDRAWN”:GOTO6.5.  IFA=BANDB=CTHENPRINT“EQUILATERAL”ELSEIFA!=BANDB!=CTHENPRINT“SCALENE”ELSEPRINT“ISOSCELES”6.STOP

AlgorithmExampleConstruct an algorithm for incremenIng the value of a variable that startswith aniniIalvalueof1andstopswhenthevaluebecomes5.SoluIon:LetthevariableberepresentedbyC.Thealgorithmforthesaidproblemisgivenasfollows:1.  START2.  Cß13.  WHILEC<=54.  BEGIN5.  PRINTC6.  CßC+17.  END

AlgorithmExampleWriteanalgorithmfortheaddiIonofNgivennumbers.SoluIon:LetthesumofNgivennumbersberepresentedbyS.1.  START2.  PRINT“HOWMANYNUMBERS?”3.  INPUTN4.  Sß05.  Cß16.  PRINT“ENTERNUMBER”7.  INPUTA8.  SßS+A9.  CßC+110.  IFC<=NTHENGOTO611. PRINTS12. STOP

Whatisaprogramflowchart?•  Atoolusedbyprogrammerstodevelopprogramlogic

•  Logicdiagram•  DiagrammaIcrepresentaIonofalgorithm

Open Files

Read a Record

Write a Line

No Yes

Close Files Stop

Whydoprogrammersuseflowchartstodevelopprogramlogic?

•  Flowchartsareagoodvisualreferenceofwhattheprogramwilldo

•  ServeasprogramdocumentaIonandasacommunicaIonstool

•  AllowtheprogrammertotestalternaIvesoluIons

The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

Whataretheflowchartsymbols?The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

TerminalSymbolThe image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.Designates the beginning or end of a program or

routine

START STOP

Input/Output(I/O)SymbolThe image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

Denotes an operation involving an input or output device

OPEN FILES

READ A RECORD

WRITE A LINE

CLOSE FILES

ProcessSymbolThe image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

Used for move instructions and arithmeIc instructions

AVERAGE = (SCORE1 +

SCORE2) / 2

MOVE SCORE1 TO

ACCUMULATOR

DecisionSymbolThe image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

Designates that different logic paths will be followed based on a condition occurring in a program

IS A = B? Yes

CODE = ?

1 2 3 4 5

PreparaIonSymbolThe image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

Assigns initial values to areas in storage and does whatever else is necessary to get ready for processing

COUNTER = 0

AnnotaIonSymbolThe image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

Describes or shows comments on the flowchart

AVERAGE = (SCORE1 +

SCORE2) / 2

CALCULATE AVERAGE

FlowlineSymbolThe image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

Links other symbols and indicates the sequence of operations

• Normal flow is top to bottom and left to right

• Arrowheads must be used when the flow is other than the normal flow

ConnectorSymbolThe image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.Connects parts of the flowchart when the

use of flowlines would be confusing or otherwise undesirable

X : 3 A=

Off-pageConnectorSymbolThe image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.The image cannot be displayed. Your computer may not have enough memory to open the image, or the image may have been corrupted. Restart your computer, and then open the file again. If the red x still appears, you may have to delete the image and then insert it again.

Connects parts of the flowchart from one page to another

COMPAREX TO 3 =

MoreRules...•  AvoidintersecIngflowlines

STOPDevelopedByStrawberry

Morerules

•  AvoidmulIpleflowlinesenteringasymbol

ExampleinSecIon2.4(page34)

•  InstrucIons– Open–  Read– Move– Write–  Close–  Stop

•  Areasinstorage–  Inputareas– Outputareas– Workareas

Open Files

Read a Record

Write a line

Close Files

StartandStop•  Start

– FirstinstrucIonofflowchart•  Stop

– LastinstrucIonexecuted•  StartandStopinstrucIonsareinterminalsymbols

Open Files

Read a Record

Write a line

Close Files

Flowchartexampleforaddingtwonumbers

InputA,B

Print“EntervalueforAandB”

CalculateC=A+B

PrintC

STOPDevelopedByStrawberry

FlowchartExample•  DrawaflowchartforcalculaIngthesimpleinterestusingtheformula

•  SI=(P*T*R)/100•  WherePdenotestheprincipalamount,TImeandRrateofinterest.

FlowchartExample•  Drawaflowcharttofindthesumofthefirst50naturalnumbers.

FlowchartExample•  DrawaflowcharttofindthelargestofthreenumbersA,BandC.

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