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Learn C Programming

A free, interactive online C course. You write C on every lesson — variables, control flow, functions, pointers, memory management — with AI hints when something segfaults, and a free certificate when you finish.

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  • Beginner friendly
  • sparkles iconAI-assisted coding help
  • hint iconHands-on interactive lessons
  • volume On iconAudio narration on every lesson
  • quiz iconQuizzes to test your knowledge
  • certificate iconFree certificate of completion

Syllabus

3 sections4 projects187 lessons163 challenges1,042 quiz questions
  1. Section 1

    Fundamentals

    Start sectionStartExpandCollapse    Build a strong foundation with essential concepts and basic skills63 lessons78 challenges381 questions

    Introduction

    4 lessons326
    • 01C LanguageChallenge
    • 02Hello World!ChallengeQuiz
    • 03CommentsQuiz
    • 04Basic Program StructureChallengeQuiz

    Variables

    11 lessons1485
    • 01Data TypesChallengeQuiz
    • 02IntegerChallengeQuiz
    • 03Float - DoubleChallengeMasteryQuiz
    • 04CharactersChallengeQuiz
    • 05BooleansChallengeMasteryQuiz
    • 06ConstantsChallengeQuiz
    • 07printf BasicsChallengeQuiz
    • 08Variable Naming RulesChallengeQuiz
    • 09Type Casting Part 1ChallengeMasteryQuiz
    • 10Type Casting Part 2ChallengeQuiz
    • 11Recap ChallengeChallenge

    Operators

    9 lessons1161
    • 01Arithmetic OperatorsChallengeQuiz
    • 02Modulo OperatorChallengeMasteryQuiz
    • 03Increment/DecrementChallengeQuiz
    • 04Assignment OperatorsChallengeQuiz
    • 05Relational OperatorsChallengeQuiz
    • 06Logical Operators Part 1ChallengeQuiz
    • 07Logical Operators Part 2ChallengeQuiz
    • 08Logical Operators Part 3ChallengeMasteryQuiz
    • 09Recap ChallengeChallenge

    Control Flow

    7 lessons944
    • 01If StatementChallengeQuiz
    • 02If - ElseChallengeQuiz
    • 03Else-IfChallengeMasteryQuiz
    • 04Switch CaseChallengeMasteryQuiz
    • 05Ternary Conditional OperatorChallengeQuiz
    • 06Recap ChallengeChallenge
    • 07Nested If - ElseChallengeQuiz

    Input & Output

    5 lessons626
    • 01Format SpecifiersChallengeQuiz
    • 02scanf BasicsChallengeMasteryQuiz
    • 03Recap Challenge #1Challenge
    • 04Input ValidationChallengeQuiz
    • 05Recap Challenge #2Challenge

    Loops

    9 lessons1053
    • 01For LoopChallengeMasteryQuiz
    • 02While LoopChallengeQuiz
    • 03Do While LoopChallengeQuiz
    • 04BreakChallengeQuiz
    • 05ContinueChallengeQuiz
    • 06Recap Challenge #1Challenge
    • 07Nested LoopsChallengeMasteryQuiz
    • 08Infinite LoopsQuiz
    • 09Recap Challenge #2Challenge

    Functions

    7 lessons1039
    • 01Declare a FunctionChallengeQuiz
    • 02Return TypesChallengeMasteryQuiz
    • 03ParametersChallengeMasteryQuiz
    • 04Recap Challenge #1Challenge
    • 05Recursion BasicsChallengeMasteryQuiz
    • 06Function PrototypesChallengeQuiz
    • 07Recap Challenge #2Challenge

    Arrays

    8 lessons1247
    • 01Declaring ArraysChallengeQuiz
    • 02Accessing ElementsChallengeQuiz
    • 03Modifying ElementsChallengeMasteryQuiz
    • 04Multidimensional ArraysChallengeMasteryQuiz
    • 05Recap Challenge #1Challenge
    • 06Arrays as Function ArgumentsChallengeMasteryQuiz
    • 07Array AlgorithmsChallengeMasteryQuiz
    • 08Recap Challenge #2Challenge

    Final Challenges

    3 lessons3
    • 01GradesChallenge
    • 02PeaksChallenge
    • 03TVChallenge
  2. Section 2

    Logic & Flow

    Start sectionStartExpandCollapse    Master advanced C programming with a focus on data structures and flow control. Learn to work with complex arrays, collections, error handling, and time management.63 lessons52 challenges345 questions2 projects

    Pointers Fundamentals

    6 lessons540
    • 01What is a Pointer?Quiz
    • 02Declaring PointersChallengeQuiz
    • 03The Address-Of Operator (&)ChallengeQuiz
    • 04The Dereference Operator (*)ChallengeQuiz
    • 05NULL PointersChallengeQuiz
    • 06Recap: Pointer BasicsChallenge

    Pointers and Arrays

    5 lessons531
    • 01Array Names as PointersChallengeQuiz
    • 02Array Elements - PointersChallengeQuiz
    • 03Pointer ArithmeticChallengeQuiz
    • 04Comparing PointersChallengeQuiz
    • 05Recap: Pointer Array TraversalChallenge

    Character Arrays and Strings

    8 lessons858
    • 01Strings as char ArraysChallengeQuiz
    • 02The Null TerminatorChallengeQuiz
    • 03String Input with scanfChallengeQuiz
    • 04Using strlen()ChallengeQuiz
    • 05Using strcpy()ChallengeQuiz
    • 06Using strcat()ChallengeQuiz
    • 07Using strcmp()ChallengeQuiz
    • 08Recap: Basic String FunctionsChallenge

    Project: Simple Text Utility

    Project5 lessons1
    • 01Project OverviewChallenge
    • 02Counting CharactersProject
    • 03Counting VowelsProject
    • 04Convert to UppercaseProject
    • 05Final OutputProject

    Pointers and Functions

    6 lessons641
    • 01Pass-by-ValueChallengeQuiz
    • 02Passing Pointers to FunctionsChallengeQuiz
    • 03Modifying Vars via PointersChallengeQuiz
    • 04A Classic Example: SwapChallengeQuiz
    • 05Passing Arrays to FunctionsChallengeQuiz
    • 06Recap: Function Pointer ArgsChallenge

    Memory Management

    7 lessons652
    • 01Stack vs. Heap MemoryQuiz
    • 02Dynamic Allocation - malloc()ChallengeQuiz
    • 03Using sizeof() for AllocationChallengeQuiz
    • 04Checking Allocation FailureChallengeQuiz
    • 05Freeing Memory with free()ChallengeQuiz
    • 06Allocating with calloc()ChallengeQuiz
    • 07Recap: Dynamic ArrayChallenge

    Structures (structs)

    6 lessons540
    • 01What is a Struct?Quiz
    • 02Declaring a StructChallengeQuiz
    • 03Creating Struct VariablesChallengeQuiz
    • 04Accessing Struct MembersChallengeQuiz
    • 05Initializing StructsChallengeQuiz
    • 06Recap: Student Data StructChallenge

    Structs and Pointers

    6 lessons643
    • 01Pointers to StructsChallengeQuiz
    • 02The Arrow Operator (->)ChallengeQuiz
    • 03Passing Structs by ValueChallengeQuiz
    • 04Passing Struct PointersChallengeQuiz
    • 05Dynamic Allocation of StructsChallengeQuiz
    • 06Recap: Modifying Struct - PtrChallenge

    Project: Simple Contact Entry

    Project5 lessons1
    • 01Project: Define Contact StructChallenge
    • 02Function to Create a ContactProject
    • 03Function to Populate a ContactProject
    • 04Function to Display a ContactProject
    • 05Putting It All TogetherProject

    Enums and Typedef

    6 lessons640
    • 01enum for Named ConstantsChallengeQuiz
    • 02Declaring and Using EnumsChallengeQuiz
    • 03Enums in Switch StatementsChallengeQuiz
    • 04Using typedef for Type AliasesChallengeQuiz
    • 05typedef with StructsChallengeQuiz
    • 06Recap: Typedef & Enum PracticeChallenge

    Final Recap Challenges

    3 lessons3
    • 01Recap: Dynamic String ConcatChallenge
    • 02Recap: Array of StructsChallenge
    • 03Recap: Word Frequency CounterChallenge
  3. Section 3

    Object Oriented Programming

    Start sectionStartExpandCollapse    Discover how to organize code with classes, objects, and reusable structures61 lessons50 challenges316 questions2 projects

    Modular Programming Basics

    5 lessons433
    • 01Header FilesQuiz
    • 02Include GuardsChallengeQuiz
    • 03Source FilesChallengeQuiz
    • 04Static FunctionsChallengeQuiz
    • 05Recap: Modular CalculatorChallenge

    Objects and Methods

    6 lessons642
    • 01Structs as ObjectsChallengeQuiz
    • 02The 'Self' PointerChallengeQuiz
    • 03Const CorrectnessChallengeQuiz
    • 04Pointer vs ValueChallengeQuiz
    • 05Helper MethodsChallengeQuiz
    • 06Recap: Point ManagerChallenge

    Object Lifecycle

    5 lessons533
    • 01Constructor PatternChallengeQuiz
    • 02Destructor PatternChallengeQuiz
    • 03Stack InitializationChallengeQuiz
    • 04Deep CopyChallengeQuiz
    • 05Recap: String WrapperChallenge

    Encapsulation

    5 lessons435
    • 01Opaque Pointers ConceptQuiz
    • 02Defining Opaque StructsChallengeQuiz
    • 03Getters and SettersChallengeQuiz
    • 04Validation in SettersChallengeQuiz
    • 05Recap: Secret BoxChallenge

    Project: Simple Bank Account

    Project6 lessons1
    • 01Project SetupChallenge
    • 02Implementation of AccountProject
    • 03Deposit LogicProject
    • 04Withdraw LogicProject
    • 05Get BalanceProject
    • 06Project Finale: Main LoopProject

    Inheritance via Composition

    5 lessons531
    • 01Struct EmbeddingChallengeQuiz
    • 02The First Member RuleChallengeQuiz
    • 03Accessing Parent MembersChallengeQuiz
    • 04UpcastingChallengeQuiz
    • 05Recap: Shape HierarchyChallenge

    Function Pointers

    5 lessons534
    • 01Declaring Function PointersChallengeQuiz
    • 02Calling Function PointersChallengeQuiz
    • 03Typedef for Function PointersChallengeQuiz
    • 04Passing Functions as ArgumentsChallengeQuiz
    • 05Recap: Calculator DispatchChallenge

    Polymorphism

    6 lessons641
    • 01Function Pointers in StructsChallengeQuiz
    • 02Simulating MethodsChallengeQuiz
    • 03The Interface ConceptChallengeQuiz
    • 04Implementing InterfacesChallengeQuiz
    • 05Polymorphic IterationChallengeQuiz
    • 06Recap: GreeterChallenge

    Project: Shape Drawer

    Project5 lessons1
    • 01Project OverviewChallenge
    • 02Circle ImplementationProject
    • 03Rectangle ImplementationProject
    • 04Polymorphic UsageProject
    • 05Shape ContainerProject

    Generic Containers

    5 lessons534
    • 01Void Pointers RecapChallengeQuiz
    • 02Generic WrapperChallengeQuiz
    • 03Generic SwapChallengeQuiz
    • 04Generic CompareChallengeQuiz
    • 05Recap: Generic ArrayChallenge

    Design Patterns in C

    4 lessons425
    • 01Singleton PatternChallengeQuiz
    • 02Factory PatternChallengeQuiz
    • 03Iterator PatternChallengeQuiz
    • 04Recap: Logger FactoryChallenge

    Final Challenges

    4 lessons48
    • 01RPG CharacterChallenge
    • 02Dynamic String BuilderChallenge
    • 03Generic StackChallenge
    • 04Event SystemChallengeQuiz

Why learn C with Coddy

  • Write and run real C code in your browser. No GCC install, no Makefile, no toolchain setup. Each exercise compiles your C program server-side and shows the output instantly.
  • C the way it's actually used: pointers and references, arrays, strings, structs, dynamic memory with malloc and free, file I/O. The C foundations every systems programmer needs.
  • AI hints help you read and fix C compiler errors and segfaults so the language feels approachable instead of cryptic from day one.
  • Free C programming certificate when you finish the course. A credible signal for systems, embedded, OS, and game-engine roles where C fluency is expected.

Frequently asked questions about learning C

Is C hard to learn?

C has a smaller feature set than most modern languages, but it makes you confront pointers and manual memory management early — which is why it has a reputation for being difficult. The course introduces those ideas one step at a time, with hands-on exercises after every concept, so the hard parts don't all hit at once.

Should I learn C or C++ first?

For embedded, OS-level, or low-level systems work, start with C — it's smaller and closer to the metal. For application development, game engines, or modern systems work, C++ is the more common choice and gives you a gentler ramp through classes before you have to manage memory by hand.

How long does it take to learn C programming?

C basics — variables, conditionals, loops, functions — take two to four weeks of daily practice. Becoming comfortable with pointers, structs, and dynamic memory usually takes another one to three months. Mastery (system-level code, performance work, large C codebases) is a multi-year arc.

Can I learn C programming online for free?

Yes. The interactive C course is free — full lessons, coding exercises, quizzes, and a certificate of completion. The C compiler runs server-side, so you don't need to install GCC, Clang, or any IDE locally to start writing C.

Do I need to install a C compiler to take this course?

No. Every C exercise compiles in a sandboxed environment and shows the output next to your code. There's no Makefile, no IDE, no toolchain to configure.

Do I get a certificate after the C programming course?

Yes. Finishing the C programming course gives you a free certificate of completion you can add to your resume or share on LinkedIn — useful alongside any systems-programming projects or GitHub repos you've built.
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