Table Of ContentContents
Introduction 1
IntroductiontoProgrammingLanguages . . . . . . . . . . . . . . . . . . . . . . . . . . 1
IntroductiontoPython . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
AdvantagesofPython . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
InstallingPythoninWindows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
InstallingPythoninmacOS(Apple) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
ExecutionModes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
InteractiveModeofExecution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
ScriptModeofExecution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
PythonFundamentals 11
Tokens: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Tokens: Keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Tokens: Identifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Tokens: Literals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Tokens: Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Tokens: Delimiters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
CharacterSet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
BlocksandIndentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Variables,Objects&DataTypes 21
WhatareObjects&Variables? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Variables&AssignmentStatements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Built-inDataTypes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
TypeChecking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
TypeCasting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Mutable&ImmutableDataTypes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Input/Output 31
HowtoAcceptUserInput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
DisplayingOutput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Operators&Expressions 35
IntroductiontoOperators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
ArithmeticOperators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
RelationalOperators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
AssignmentOperators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
LogicalOperators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
IdentityOperators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
MembershipOperators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
OperatorPrecedencewithExamples . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Errors&ExceptionHandling 49
ErrorTypes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
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SyntaxError . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
RuntimeError . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
LogicalError . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Exceptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
ExceptionHandling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
ControlFlow 57
IntroductiontoControlFlow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
SequentialFlow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
SelectionStatements: if.. else . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Iteration: for . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Iteration: while . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
JumpStatements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
NestedLoops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Strings 71
Strings: Introduction&Creation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
AccessingCharactersofaString . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
StringOperations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
IntroductiontoStringMethods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
ConvertCaseofStrings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
CheckCharactersofaString . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
SplitaString . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
StripCharactersfromaString . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
CheckPrefixorSuffixinaString . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Find&ReplaceCharactersinaString . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
TraversingaString . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
List 83
WhatisaPythonList? HowtoCreateaList? . . . . . . . . . . . . . . . . . . . . . . . . 83
AccessingItemsofaList . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
ModifyingaList . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
RemovingItemfromaList . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
ListOperations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
TraversingaList . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Built-inFunctionsthatcanbeusedforaList . . . . . . . . . . . . . . . . . . . . . . . . 88
IntroductiontoListMethods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
AddingItemstoaList . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
RemovingItemsfromaList . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
CountingorLocatingItemsinaList . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
ReversingItems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
SortingaList . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
CopyingaList . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
NestedList . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
ListComprehension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
SamplePrograms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Tuple 97
ListvsTuple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
HowtoCreateTuple? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
WhatisaSingleton? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
AccessingItemsofaTuple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
TuplesareImmutable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
TupleOperations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
TraversingaTuple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Built-inFunctionsthatcanbeusedforaTuple . . . . . . . . . . . . . . . . . . . . . . . 101
LocatingItemsinaTuple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
CountingtheOccurrenceofanItem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
NewTuplewithReversedItems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
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NewTuplewithSortedItems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
NestedTuple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
UnderstandingtheImmutableNatureofTuples . . . . . . . . . . . . . . . . . . . . . . . 103
Dictionary 105
WhatisaDictionary? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
HowtoCreateaDictionary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
AccessingItems(Key:Value)ofaDictionary . . . . . . . . . . . . . . . . . . . . . . . . . 106
UpdatingaDictionary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
RemovinganItem(Key:Value)fromaDictionary . . . . . . . . . . . . . . . . . . . . . . . 108
DictionaryOperations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
TraversingaDictionary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Built-inFunctionsforaDictionary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
CreatingaCopyofaDictionary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
NestedDictionary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
SamplePrograms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
PythonStandardLibrary 115
Built-inFunctions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
MathematicalFunctions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
TypeFunctions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
I/OFunctions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Base/UnicodeConversionFunctions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
WhatareBuilt-inModules? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
mathModule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
randomModule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
statisticsModule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
FileHandling 123
FileHandlinginPython-Introduction&Overview . . . . . . . . . . . . . . . . . . . . . . 123
TextFilesvsBinaryFiles-UseCase,FileFormats,Examples . . . . . . . . . . . . . . . . 123
FileOpening&Closing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
FileReading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
WritingaFile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Reading&WritingBinaryFilesusing pickle Module . . . . . . . . . . . . . . . . . . 129
Reading&WritingaCSVFileusing csv Module . . . . . . . . . . . . . . . . . . . . . 131
UserDefinedFunctions,Modules&Packages 135
UserDefinedFunctions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
FunctionStructure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
ParametersandArguments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
ScopeofVariables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
PassingObjectsofMutableTypetoaFunction . . . . . . . . . . . . . . . . . . . . . . . 139
WhatisaModule? HowtoCreateaModule? . . . . . . . . . . . . . . . . . . . . . . . . 140
ExecutableScripts/Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
WhatisaPackage? IntroductiontoPyPi. HowtoCreateaPythonPackage? . . . . . . . . 142
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Introduction
Introduction to Programming Languages
Intoday’sdigitalera,wedependoncomputers,smartphonesandtheinternettoperformaplethoraof
tasks,like:
• Amathematicaltask,suchasfindingthesquarerootofanumberorsolvingasetofsimultaneous
equations.
• Atext-basedtasksuchasreadingadocumentandperformingsearch/replace.
• Streamingandplayingmultimediafilescontainingaudioandvideo.
• Usingasearchenginetofindandvisitawebsite.
• Playinganonlinemultiplayergamewithfriends.
• andmanymore…
Softwaresplayanimportantroleastheytranslatehumanactivityintocorrespondingmachineinstructions
whichareexecutedtoaccomplishthesetasks.
A software is a collection of programs where each program provides a sequence of instructions
specifyinghowthecomputershouldact.
Theseinstructionshavetobeprovidedinmachinelanguageorlowlevellanguage(0sand1s)thatis
difficulttoreadorwriteforahumanbeing.
Thisledtotheinventionofhigh-levelprogramminglanguagesinwhichprogramscanbeeasilywritten
andmanaged. Thehuman-readableprogramswrittenusinghigh-levellanguagesareconvertedinto
computer-readablemachinecodeorbytecodeusingcompilersorinterpreters.
Therearemanyhigh-levelprogramminglanguagesthatarecurrentlyinwideuse.
Some of the popular languages are Java, C, C++, C#, Go, Swift, JavaScript, PHP, Dart, Kotlin and
Python.
Introduction to Python
GuidovanRossumstartedthedevelopmentofPythoninDecember1989. Hereleasedthefirstversion
(0.9.9)ofPythonforgeneralpubliconFebruary20,1991.
Thelanguageevolvedoverthenextfewdecadesandsodiditsdefinition,thecurrentversionofwhich
isstatedbelow:
Python is a high-level, interpreted, object-oriented programming language with dynamic
semantics.
LetusbreakdownandanalyzetheabovedefinitiontogainabetterunderstandingofPython:
High-level
Pythonisahigh-levelprogramminglanguagewhichcanbeusedtowriteaprograminnaturallanguage
(english)makingitreadable,writable,shareableandmanageable.
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WhiledevelopingaPythonprogramoneisnotrequiredtohandlethevariouscomponentsofcomputer
architecturelikeregisters,memoryaddressesandcallstackswhichhavetobehandledifanassembly
languageoralow-levellanguageisusedfordevelopment.
Python includes high-level language features like variables, data structures (lists, dictionaries, etc.),
objects,expressions,modules,classes,functions,loops,threads,filehandling,stringhandling,error
handlingandothercomputerscienceabstractionconcepts.
Interpreted
IntraditionalprogramminglanguageslikeCorC++,codesarecompiledintocomputer-readablemachine
codebeforeitcanbeexecuted.
PythonisaninterpretedlanguagewherethePythoninterpreterreadsandexecutestheprogramline
byline.
Theprocessismoretimeconsumingcomparedtocompiledcodeexecution,butallowsfasterdevelop-
mentasonedoesnothavetogothroughtheentirecompilationstepduringtestinganddebugging.
Also, the code can run on any platform as long as it has a valid Python installation (which includes
interpreter)asthereisnogenerationofplatformdependentbinaries.
Object-oriented
PythondoesnotenforceObject-orientedprogramming(OOP),butcompletelysupportsit.
AprogrammercandefineClassesspecifyingthedataintheformofattributes(orproperties)andsome
programminglogicintheformofmemberfunctions(ormethods). Onceaclassisdefined,theusercan
createaninstanceofthatclasswhichisknownasanobject.
InPython,everything( int , list , dict ,etc.) isanobject. Wewillcovermoreaboutobjectsin
detailinthelatersections.
DynamicSemantics
AsPythonisaninterpretedlanguageinwhichthecodeisexecutedline-by-line,apythonstatementor
expressionisevaluatedduringrun-time. Thisallowsdynamictyping(typeofavariablecanchangeover
itslifetime)andcreationofdynamicobjectsduringrun-time,whichprovidesmoreflexibility,usability
andfewerlinesofcodeascomparedtostatically-typedcompiledlanguageslikeC/C++.
Advantages of Python
ThekeyadvantagesofPythonareasfollows:
1. EasytoLearn
ThePythonprogramminglanguageiseasytolearnwithlowtechnicalandconceptualoverhead. This
makesitanideallanguageforbeginnerstolearnprogramming.
2. ClearSyntax&FewerLinesofCode
Python’ssimpleandeasytolearnsyntaxincreasescodereadabilityandleadstofewerlinesofcode.
AtypicaltaskwhichrequiresanaverageoftwentylinesofcodeinCandseveninJavacanoftenbe
donewithjustonelineinPython.
Also,duetofewerlinesofcodethechancesofmakinganyerrorissignificantlyreduced.
3. OpenSource
Python is an open source programming language, so anyone can view and contribute to its source
code.
4. Portable&PlatformIndependent
The Python programming language is portable & platform independent as it can work on any Linux,
MacOSorWindowsdevice.
5. StandardLibrary&PythonPackages
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PythonhasarichandextensiveStandardLibrary,acollectionofpredefinedfunctionsforvarioustasks.
Python programmers also have at their disposal the vast ecosystem of more than 250,000 commu-
nitycontributedlibrariesinthePythonPackageIndex(PyPI),whereonecanfindasolutiontoevery
conceivabletask.
6. WebApplicationDevelopment
Someofthemostpopularwebdevelopmentframeworks(django,flask,etc.) arewritteninPython. This
coupledwiththeavailablityofpackagestoconnecttoanydatabasemakesPythonagreatchoicefor
webapplicationdevelopment.
Installing Python in Windows
Let’sstartwiththePython3installationprocessonWindowsoperatingsystem.
Step1: DownloadInstaller
DownloadthelatestWindowsinstallerfromthePythonSoftwareFoundationwebsite.
Step1: DownloadInstaller
Step2: InstallPython3
Oncethedownloadiscompletedouble-clickandrunit.
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Step2: InstallPython3
✅
Selectthecheckbox Add Python 3.9 to PATH . Thiswillenableyoutoinstallpythonpackages
andrunpythonscriptviacommand-line.
Hit Install Now andcompletethesetup.
Step3: VerifyInstallation
Oncethesetupiscomplete,clickonthe Start menuandopen Python 3.9 -> IDLE (Python 3.9 64 bit)
tolaunchthePythoninterpreter.
Step3: LaunchPythonInterpreter
Python3.9isnowsuccessfullyinstalledonyourcomputer.
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Step3: VerifyInstallation
Installing Python in macOS (Apple)
Let’sstartwiththePython3installationprocessonmacOSoperatingsystem.
Step1: DownloadInstaller
DownloadthelatestmacOSinstallerfromthePythonSoftwareFoundationwebsite.
Step1: DownloadInstaller
Step2: InstallPython3
Oncethedownloadiscompletedouble-clickandrunit.
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