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

Start

Open Files

Read a Record

Write a Line

EOF?

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

No

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 =

< >

p. 2B


MoreRules...•  AvoidintersecIngflowlines

START

STOP

B

C

B

A

C

A

START

STOPDevelopedByStrawberry

Morerules

•  AvoidmulIpleflowlinesenteringasymbol


ExampleinSecIon2.4(page34)

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

•  Areasinstorage–  Inputareas– Outputareas– Workareas

Start

Open Files

Read a Record

Write a line

Close Files

Stop


StartandStop•  Start

– FirstinstrucIonofflowchart•  Stop

– LastinstrucIonexecuted•  StartandStopinstrucIonsareinterminalsymbols

Start

Open Files

Read a Record

Write a line

Close Files

Stop


Flowchartexampleforaddingtwonumbers

START

InputA,B

Print“EntervalueforAandB”

CalculateC=A+B

PrintC

STOPDevelopedByStrawberry

FlowchartExample•  DrawaflowchartforcalculaIngthesimpleinterestusingtheformula

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


FlowchartExample•  Drawaflowcharttofindthesumofthefirst50naturalnumbers.


FlowchartExample•  DrawaflowcharttofindthelargestofthreenumbersA,BandC.


computer programming –i - strawberry -...

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