ModernC++
Programming
1.Introduction
FedericoBusato
2025-04-14
AboutMotivation1/5
“Whenrecruitingresearchassistants,Ilookatgradesasthelastindi-
cator.Ifindthatimagination,ambition,initiative,curiosity,drive,
arefarbetterpredictorsofsomeonewhowilldousefulworkwithme.Of
course,thesecharacteristicsarethemselvescorrelatedwithhighgrades,
butthereissomethingtobesaidaboutastudentwhodecidesthata
givencourseisawasteoftimeandthatheworksonasideprojectin-
stead.
Breakthroughsdon’thappeninregularscheduledclasses,theyhappen
insideprojects.Wewantpeoplewhocompletetheworktheywereas-
signed,butwealsoneedpeoplewhocanreflectcriticallyonwhat
isgenuinelyimportant"
DanielLemire,Prof.attheUniversityofQuebec
2/55
AboutMotivation2/5
Academicexcellenceisnotastrongpredictor
ofcareerexcellence
“Acrossindustries,researchshowsthatthecorrelationbetweengrades
andjobperformanceismodestinthefirstyearaftercollegeandtrivial
withinahandfulofyears...
Academicgradesrarelyassessqualitieslikecreativity,leadershipandteam-
workskills,orsocial,emotionalandpoliticalintelligence.Yes,straight-A
studentsmastercramminginformationandregurgitatingitonexams.
Butcareersuccessisrarelyaboutfindingtherightsolutiontoa
problem—it’smoreaboutfindingtherightproblemtosolve...”
3/55
AboutMotivation3/5
“GettingstraightA’srequiresconformity.Havinganinfluential
careerdemandsoriginality.
ThismightexplainwhySteveJobsfinishedhighschoolwitha2.65
G.P.A.,J.K.RowlinggraduatedfromtheUniversityofExeterwith
roughlyaCaverage,andtheRev.Dr.MartinLutherKingJr.gotonly
oneAinhisfouryearsatMorehouse
Ifyourgoalistograduatewithoutablemishonyourtranscript,you
enduptakingeasierclassesandstayingwithinyourcomfortzone.If
you’rewillingtotoleratetheoccasionalB...Yougainexperiencecoping
withfailuresandsetbacks,whichbuildsresilience”
4/55
AboutMotivation4/5
“Straight-Astudentsalsomissoutsocially.Moretimestudyingin
thelibrarymeanslesstimetostartlifelongfriendships,joinnewclubsor
volunteer...Lookingback,Idon’twishmygradeshadbeenhigher.IfI
coulddoitoveragain,I’dstudyless”
AdamGrant,theNewYorkTimes
www.nytimes.com/2018/12/08/opinion/college-gpa-career-success.html
5/55
AboutMotivation5/5
“Gota2.4GPAmyfirstsemesterincollege.ThoughtmaybeIwasn’t
cutoutforengineering.TodayI’velandingtwospacecraftonMars,and
designingoneforthemoon.
STEMishardforeveryone.Gradesultimatelyaren’twhatmatters.
Curiosityandpersistencematter”
BenCichy,ChiefSoftwareEngineer,
NASAMarsScienceLaboratory
twitter.com/bencichy/status/1197752802929364992?s=20
6/55
AboutProgramming1/2
“Andprogrammingcomputerswassofascinating.Youcreateyour
ownlittleuniverse,andthenitdoeswhatyoutellittodo”
VintCerf,TCP/IPco-inventorandTuringAward
“Mostgoodprogrammersdoprogrammingnotbecausetheyexpectto
getpaidorgetadulationbythepublic,butbecauseitisfuntoprogram”
LinusTorvalds,principaldeveloperoftheLinuxkernel
“Youmightnotthinkthatprogrammersareartists,butprogramming
isanextremelycreativeprofession.It’slogic-basedcreativity”
JohnRomero,co-founderofidSoftware
7/55
AboutProgramming2/2
CreativityProgrammingisextremelycreative.Theabilitytoperceivetheproblemin
anovelway,providenewandoriginalsolutions.Creativityallows
recognizingandgeneratingalternatives
FormofArtArtistheexpressionofhumancreativeskills.Everyprogrammerhashis
ownstyle.Codesandalgorithmsshoweleganceandbeautyinthesame
wayaspaintingormusic
LearnProgramminggivestheopportunitytolearnnewthingseveryday,
improveownskillsandknowledge
ChallengeProgrammingisachallenge.Achallengeagainstyourself,theproblem,
andtheenvironment
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Knowledge-ExperienceRelation
9/55
LearningandThinking
“Insoftwaredevelopment,learningisnotabigpartofthejob.
Itisthejob."
WoodyZuill
“Programmingisnotabouttyping,it’saboutthinking."
RichHickey
10/55
TheAssemblyProgrammingLanguage
Alongtimeago,inagalaxyfar,
faraway....therewasAssembly
•Extremelysimpleinstructions
•Requireslotsofcodetodosimpletasks
•Canexpressanythingyourcomputercando
•Hardtoread,write
•...redundant,boringprogramming,bugspro-
liferation
main:
.Lfunc_begin0:
pushrbp
.Lcfi0:
.Lcfi1:
movrbp,rsp
.Lcfi2:
subrsp,16
movabsrdi,.L.str
.Ltmp0:
moval,0
callprintf
xorecx,ecx
movdwordptr[rbp-4],eax
moveax,ecx
addrsp,16
poprbp
ret
.Ltmp1:
.Lfunc_end0:
.L.str:
.asciz"HelloWorld\n"
11/55
ALittleHistoryofC1/3
Inthe1969DennisM.RitchieandKenThompson(AT&T,BellLabs)workedon
developinganoperatingsystemforalargecomputerthatcouldbeusedbyathousand
users.ThenewoperatingsystemwascalledUNIX
Thewholesystemwasstillwritteninassemblycode.BesidesassemblerandFortran,
UNIXalsohadaninterpreterfortheprogramminglanguageB.Ahigh-levellanguage
likeBmadeitpossibletowritemanypagesofcodetaskinjustafewlinesofcode.In
thiswaythecodecouldbeproducedmuchfasterthaninassembly
AdrawbackoftheBlanguagewasthatitdidnotknowdata-types(everythingwas
expressedinmachinewords).AnotherfunctionalitythattheBlanguagedidnotprovide
wastheuseof“structures”.ThelackofthesethingsformedthereasonforDennis
M.RitchietodeveloptheprogramminglanguageC.In1988theydeliveredthefinal
standarddefinitionANSIC
12/55
ALittleHistoryofC2/3
DennisM.RitchieandKenThompson
#include"stdio.h"
intmain(){
printf("HelloWorld\n");
}
13/55
ALittleHistoryofC3/3
AreasofApplication:
•UNIXoperatingsystem
•Computergames
•Duetotheirpowerandeaseofuse,Cwereusedintheprogrammingofthe
specialeffectsforStarWars
StarWars-TheEmpireStrikesBack
14/55
ALittleHistoryofC++1/3
TheC++programminglanguage(originallynamed“CwithClasses")wasdevised
byBjarneStroustrupalsoanemployeefromBellLabs(AT&T).Stroustrupstarted
workingonCwithClassesin1979.(The++isClanguageoperator)
ThefirstcommercialreleaseoftheC++languagewasinOctober1985
15/55
ALittleHistoryofC++2/3
TherootsofC++
“TheEvolutionofC++Past,Present,andFuture”,B.Stroustrup,CppCon16
16/55
ALittleHistoryofC++3/3
17/55
AboutEvolution
“Ifyou’reteachingtodaywhatyouwereteachingfive
yearsago,eitherthefieldisdeadoryouare”
NoamChomsky
18/55
WhyC++issoPopular?1/2
Theremaybemorethan200billionlines
ofC/C++codeglobally
•PerformanceisthedefiningaspectofC++.Nootherprogramming
languageprovidestheperformance-criticalfacilitiesofC++
•Providetheprogrammercontrolovereveryaspectofperformance
•Leavenoroomforalowerlevellanguage
Totalnumberoflinesofallcodeinuse?
22/55
WhyC++issoPopular?2/2
•Ubiquity.C++canrunfromalow-powerembeddeddevicetolarge-scale
supercomputers
•Multi-Paradigm.Allowwritingefficientcodewithoutlosinghigh-level
abstraction
•Allowwritinglow-levelcode.Drivers,kernels,assembly(asm),etc.
•Ecosystem.Manysupporttoolssuchasdebuggers,memorycheckers,
coverage,staticanalysis,profiling,etc.
•Maturity.C++hasa40yearshistory.Manysoftwareproblemshavebeen
alreadyaddressedanddevelopingpracticeshavebeeninvestigated
23/55
AreasofApplication1/2
•Operatingsystems:Windows,Android,OSX,Linux
•Compilers:LLVM,Swiftcompiler
•ArtificialIntelligence:TensorFlow,Caffe,MicrosoftCognitiveToolkit
•ImageEditing:AdobePremier,Photoshop,Illustrator
•Webbrowser:Firefox,Chrome,etc.+WebAssembly
•High-PerformanceComputing:drugdevelopingandtesting,largescaleclimate
models,physicsimulations
•Embeddedsystems:IoT,networkdevices(e.g.GSM),automotive
•GoogleandMicrosoftuseC++forwebindexing
24/55
AreasofApplication2/2
•ScientificComputing:CERN/NASA*,SETI@home,Folding@home
•Database:MySQL,ScyllaDB
•VideoGames:UnrealEngine,Unity
•Entertainment:Movierendering(seeInterstellarblackholerendering),
virtualreality
•Finance:electronictradingsystems(Goldman,JPMorgan,DeutscheBank)**
...andmanymore
*TheflightcodeoftheNASAMarsdroneforthePerseveranceMission,aswellastheWebb
telescopesoftware,aremostlywritteninC++github.com/nasa/fprime,JamesWebbSpace
Telescope’sFullDeployment
**C++isthenewPython
25/55
WhyC++issoImportant?
TheEndofHistoricalPerformanceScaling
Performancelimitationsinfluencealgorithmdesign
andresearchdirections
26/55
Performance1/4
8.23
21.47
21.9622.1
26.61
300
360
660
780
0
100
200
300
400
500
600
700
800
900
C++GOSWIFTJAVANode.jsPHPRubyPerlPython3
Execution TIme (S)
Programming Language
N-BODYSIMULATION
PROGRAMMINGLANGUAGESPERFORMANCECOMPARISON
28/55
Performance3/4
”ANewGoldenAgeforComputerArchitecture“,J.L.Heneessey,D.A.Patterson,2019
30/55
Performance/ExpressivenessTrade-off
1
10
100
1,000
10,000
100,000
1,000,000
AssemblyCC++JavaJSPython
INSTRUCTIONS PER LINE
Mandelbrot Static Instructions per Line
32/55
C++Philosophy-Performance1/3
Donotsacrificeperformanceexceptasalastresort
ZeroOverheadPrinciple(zero-costabstraction)
“itbasicallysaysifyouhaveanabstractionitshouldnot
costanythingcomparedtowritetheequivalentcodeatlower
level”
“soIhavesayamatrixmultiplyitshouldbewrittenina
suchawaythatyoucouldnotdroptotheClevelofabstrac-
tionandusearraysandpointersandsuchandrunfaster”
BjarneStroustrup
36/55
C++Philosophy-TypeSafety2/3
Enforcesafetyatcompiletimewheneverpossible
StaticallyTypedLanguage
“TheC++compilerprovidestypesafetyandcatches
manybugsatcompiletimeinsteadofruntime(acritical
considerationformanycommercialapplications.)”
www.python.org/doc/FAQ.html
•Thetypeannotationmakesthecodemorereadable
•Promotecompileroptimizationsandruntimeefficiency
•Allowuserstodefinetheirowntypesystem
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C++Philosophy3/3
•Programmingmodel:compartmentalization,onlyadd
featuresiftheysolveanactualproblem,andallowfullcontrol
•Predictableruntime(underconstraints):nogarbage
collector,nodynamictypesystem→real-timesystems
•Lowresources:lowmemoryandenergyconsumption→
restrictedhardwareplatforms
•Wellsuitedforstaticanalysis→safetycriticalsoftware
•Portability→ModernC++standardsarehighlyportable
38/55
WhoisC++for?
“C++isforpeoplewhowanttousehardwareverywell
andmanagethecomplexityofdoingthatthroughabstrac-
tion”
BjarneStroustrup
“alanguagelikeC++isnotforeverybody.Itisgener-
atedviasharpandeffectivetoolforprofessionalbasicallyand
definitelyforpeoplewhoaimatsomekindofprecision”
BjarneStroustrup
39/55
WhyC++issoDifficult?1/2
...andwhyteachingC++asfirstprogramminglanguageisabadidea?
C++isthehardestlanguagefromstudentstomaster
•Morelanguagesinone
-StandardC/C++programming
-Preprocessor
-Object-Orientedfeatures
-TemplatesandMeta-Programming
•Hugesetoffeatures
•Worryaboutmemorymanagement
•Low-levelimplementationdetails:pointerarithmetic,structure,padding,
undefinedbehavior,etc.
•Frustrating:compiler/runtimeerrors(e.g.seg.fault)
41/55
WhyC++issoDifficult?2/2
“Cmakesiteasytoshootyourselfinthefoot;C++makesitharder,
butwhenyoudo,itblowsyourwholelegoff”
BjarneStroustrup,CreatoroftheC++language
“TheproblemwithusingC++...isthatthere’salreadyastrongten-
dencyinthelanguagetorequireyoutoknoweverythingbeforeyoucan
doanything”
LarryWall,CreatorofthePerllanguage
“Despitehaving20yearsofexperiencewithC++,whenIcompilea
non-trivialchunkofcodeforthefirsttimewithoutanyerrororwarning,
Iamsuspicious.Itisnot,usually,agoodsign”
DanielLemire,Prof.attheUniversityofQuebec
42/55
C++Weaknesses1/2
Backward-compatibility
‘‘Dangerousdefaultsandconstructs,oftenoriginatingfromC,cannotberemoved
oraltered”
“Despitethehardworkofthecommittee,newerfeaturessometimeshaveflaws
thatonlybecameobviousafterextensiveuserexperience,whichcannotthenbe
fixed”
“C++practicehasputanever-increasingcognitiveburdenonthedeveloperfor
whatIfeelhasbeenverylittlegaininproductivityorexpressivenessandatahugecost
tocodeclarity”
43/55
C++Alternatives:Rust
Rust(1.0,2015)hasbeenStackOverflow’smostlovedlanguageforeightyearsina
row.Rustfocusesonperformanceandzero-abstractionoverheadasC++.Itis
designedtopreventmanyvulnerabilitiesthataffectC++,especiallymemorybugs,
enforcingconstraintsatcompiletype.Inaddition,itpromotescross-platform
compatibility
“First-timecontributorstoRustprojectsareabout70timeslesslikelyto
introducevulnerabilitiesthanfirst-timecontributorstoC++projects”
Traceyetal.
1
1
GradingonaCurve:HowRustcanFacilitateNewContributorswhileDecreasing
Vulnerabilities
•CISA,NSA:TheCaseforMemorySafeRoadmap
•Octoverse:TheFastestGrowingLanguages
•SecurebyDesign:Google’sPerspectiveonMemorySafety
45/55
WhySwitchingtoaNewLanguageisHard?1/3
•Noperfectlanguage.Therearealwaysnewer’shining’languages
•Alignment.Forcealldeveloperstoswitchtothenewlanguage
•Interoperability.Hundredsofbillionlinesofexistingcode.Mustinteroperate
withCandC++codeimposingseriousdesignconstraints
•Ecosystem.Lackoftoolsandlibrariesdevelopedinthelastfourdecades
•TimeandCost.Convertingacodebaseof10millionlines:500developers,5
years,$1,400,000,000
1
1
BjarneStroustrup:DeliveringSafeC++
47/55
WhySwitchingtoaNewLanguageisHard?3/3
49/55
LanguageComplexity
Everysecondspenttryingtounderstandthe
languageisonenotspentunderstandingthe
problem
50/55
TheCourse
51/55
TheCourse
Don’tforget:Therightnameofthecourseshouldbe
“IntroductiontoModernC++Programming”
Formanytopicsinthecourse,therearemorethanonebookdevotedtopresentthe
conceptsindetail
52/55
TheCourse
Theprimarygoalofthecourseistodrivewhohaspreviousexperiencewith
C/C++andobject-orientedprogrammingtoaproficiencylevelof(C++)
programming
•Proficiency:knowwhatyouaredoingandtherelatedimplications
•Understandwhatproblems/issuesaddressagivenlanguagefeature
•Learnengineeringpractices(e.g.codeconventions,tools)andhardware/software
techniques(e.g.semantic,optimizations)thatarenotstrictlyrelatedtoC++
Whatthecourseis:
•Apracticalcourse,preferexamplestolongdescriptions
•A“quite”advancedC++programminglanguagecourse
Whatthecourseisnot:
•Atheoreticalcourseonprogramming
•Ahigh-levelconceptdescription
53/55
TheCourse
Organization:
•26lectures
•∼1,800slides
•C++03/C++11/C++14/C++17/C++20/(C++23)/(C++26)
Roadmap:
•ReviewCconceptsinC++(built-intypes,memorymanagement,preprocessing,
etc.)
•Introduceobject-orientedandtemplateconcepts
•Presenthowtoorganizethecodeandthemainconventions
•C++toolgoalsandusage(debugger,staticanalysis,etc.)
54/55
WhoIAm
FedericoBusato,Ph.D.
federico-busato.github.io
•SeniorSoftwareEngineeratNvidia,
CUDACoreComputeLibraries
•FormerleadoftheSparseLinearAlgebragroup
•Interests:
◦SparseLinearAlgebra
◦GraphAlgorithms
◦Parallel/High-PerformanceComputing
◦CodeOptimization
OnBluesky:fbusato.bsky
NOTaC++expert/“guru”,stilllearning
55/55
“WhatIcannotcreate,
Idonotunderstand"
RichardP.
Feynman
55/55
“Theonlywaytolearnanewpro-
gramminglanguageisbywritingpro-
gramsinit"
DennisRitchie
CreatoroftheCprogramminglanguage
55/55