MoreExerciseswithLoopsCS8:IntroductiontoComputerScience,Spring2019

Lecture#8

ZiadMatni,Ph.D.Dept.ofComputerScience,UCSB

Administrative•  Hw04–duenextweek•  Lab02–dueonSundaybymidnight(11:59pm)onGradescope!

•  MidtermExam#1isNEXTWEEKonWed.,May2nd–  I’llputupsampleproblemsafterWed.thisweek

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Midterm#1Exam•  May2nd,2:00–3:15PMinTHISclassroom(unlessyouareaDSPstudent)•  Come10MINUTESEARLYastheremightbepre-assignedseating•  CLOSEDBOOK!Butyoucanbring1pageofnotes

–  Single-sideonly,8.5”x11”–  Hand-writtenorcomputerprintedisOK!–  Mustturnitinwiththeexamwhendone–  Nocalculators/cellphones/anytypeofcomputer

•  BringyourUCSBIDwithyou.NOEXCEPTIONS.

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Midterm#1ExamWHAT’SONIT?!

•  Everything–  ReviewALLlectures–  ReviewALLreadings–  ReviewALLlabs–  ReviewALLhomework

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Midterm#1ExamSAMPLEQUESTIONS?!?!?!?!?!?!

•  Yes!SeeStudyGuideontheclasswebsite!

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LectureOutline•  Moreexercisewithloopsusingforandwhile

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Exercise1•  Whatwillthiscodedo?forpinrange(6,25,6):ifp%12==0: print("X",end="")else: print("O",end="")

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Exercise2•  Whatwillthiscodedo?sum=0count=0while(count<10):ifcountin(3,8): print(count/2)count+=1sum+=count

print(count,sum,sep=",")

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ClassExerciseGettogetherwith2or3otherpeoplearoundyouandanswerthisquestion.

Youcanuseyournotesfromlasttime.Youcanuseyourcomputers:

Aprimenumberisapositive,non-zerointegerthatcannotbedividedbyanyotherpositive,non-zerointeger,exceptONE(1)andITSELF.

Forexample,5isaprimenumber,but6isnot(it’sdivisibleby2andby3).Thefirstfiveprimenumbersare:2,3,5,7,and11

WriteaPythonfunction,prime(),thattakesanargumentnandreturnseitherTrue(ifnisaprimenumber)orFalse(ifnisNOTaprimenumber).

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ClassExercisedefprime(n):

p=Trueforiinrange(2,n): ifn%i==0: p=Falsereturnp

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ClassExercisedefprime(n):

p=Trueforiinrange(2,n): ifn%i==0: p=Falsereturnp

#Let’stestournewfunctionout!foriinrange(2,3000):

ifprime(i): print(i)

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BONUS:print(i,",",end="")

Exercise3TakeoutapieceofpaperandwritePythoncodethatwillgothroughallthenumbersfrom1to10(inclusiveof1and10)andprintsouttheproductofallthesenumbers.YouMUSTuseafor-looptosolvethisproblem.

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Exercise3-Solutionp=1forninrange(1,11): p=p*n #orp*=n

print(p)

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Exercise4–NestedLoops

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•  Whatwillthiscodedo?forpinrange(2):forqinrange(3): print("z",end="")

IntroducingTurtleGraphics!•  AnicewaytogetintroducedtosimplegraphicsusingPython

•  Youhavetofirstimportturtle

•  YoucanthenuseitasperthedemoI’mabouttogive…

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BasicTurtleCommandsimportturtletimmy=turtle.Turtle()#Settheturtleobject,callittimmy!timmy.forward(100) #Drawforwards100pixelstimmy.right(90) #Turntheturtle90degreestotherighttimmy.backwards(50) #Drawbackwards50pixelstimmy.left(45) #Turntheturtle45degreestothelefttimmy.color("blue")#Maketimmybluetimmy.pensize(3) #Setthewidthofthepentimmy.penup() #Putpenup(canmoveitw/odrawing)timmy.pendown() #Putpendown(candrawagain)4/25/19 Matni,CS8,Sp19 16

WhatWillTheseDo?importturtleboris=turtle.Turtle()boris.color("blue")boris.forward(100) boris.right(90)boris.forward(100) boris.right(90) boris.forward(100) boris.right(90) boris.forward(100) boris.right(90)4/25/19 Matni,CS8,Sp19 17

importturtlenatascha=turtle.Turtle()natascha.color("red")natascha.forward(100)natascha.left(60)natascha.forward(100)natascha.left(60)natascha.forward(100)natascha.left(60)natascha.forward(100)natascha.left(60)natascha.forward(100)natascha.left(60)natascha.forward(100)natascha.left(60)

YOURTO-DOsq  FinishreadingChapter5q  FinishHW4(dueTUESDAY)q  FinishLab2(turnitinbySunday)

q Whistlewhileyouwork

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