C Programming Study Plan (Beginner → Advanced)

MODULE 1 – C Foundations (Syntax & Mental Model) ✅✅✅

Goal: Understand what C is and how it differs from JS/TS

Topics

• Compilation model (preprocess → compile → link)
• main, headers, source files
• Variables, types, operators
• Control flow (if, for, while, switch)
• Functions & function prototypes
• Stack vs heap (conceptual only)
• stdio.h, printf, scanf
• No runtime safety net

Key Concepts (JS → C shift)

• No garbage collector
• No bounds checking
• No runtime type safety
• You control memory and lifetimes

Exercises

1. Write a program that prints command-line arguments (argc, argv)✅
2. Implement a calculator using switch ✅
3. Write a function that swaps two integers (first attempt will fail—learn why) ✅
4. Implement your own strlen ✅

Compile with:

gcc -Wall -Wextra -Werror

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MODULE 2 – Memory & Pointers (CORE MODULE) ✅✅✅

Goal: Become comfortable with pointers and memory ownership

Topics

• Addresses and &
• Pointers and *
• Pointer arithmetic
• NULL
• Arrays vs pointers
• Stack memory layout
• Passing by value vs by pointer

Undefined Behavior Introduced

• Dereferencing uninitialized pointers
• Out-of-bounds access
• Returning pointers to stack memory

Exercises

1. Write a function that reverses an array in place✅
2. Print memory addresses of array elements✅
3. Implement strcpy using pointers✅
4. Write a program that crashes, then explain why✅

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MODULE 3 – Dynamic Memory Allocation✅✅✅

Goal: Understand heap memory and manual lifecycle management

Topics

• malloc, calloc, realloc, free
• Ownership rules
• Memory leaks
• Double free
• Dangling pointers
• Heap vs stack lifetimes

Tools Introduced

• valgrind
• AddressSanitizer

run with:

gcc -g -Wall -Wextra -Werror main.c -o main && valgrind --leak-check=full ./main

Exercises

1. Allocate an array dynamically and fill it✅
2. Implement a dynamic string type✅
3. Write a program with a memory leak, then fix it✅
4. Re-implement strdup✅
5. Re-implement memcpy✅

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MODULE 4 – Strings & Buffers (Security-Critical)

Goal: Learn why C strings are dangerous

Topics

• Null-terminated strings
• Buffer overflow
• strcpy vs strncpy vs snprintf
• Input handling (fgets vs gets)
• Defensive coding

Undefined Behavior

• Writing past buffer end
• Missing \0
• Reading uninitialized memory

Exercises

1. Implement strlen safely✅
2. Write a safe input function using fgets✅
3. Implement string concatenation with size limits✅
4. Write a program vulnerable to buffer overflow, then fix it
5. Detect overflow using AddressSanitizer

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MODULE 5 – Structs, Enums & Data Modeling✅✅✅

Goal: Model complex data safely

Topics

• struct, typedef
• Padding & alignment
• Nested structs
• Enums and bit flags
• Ownership inside structs

Exercises

1. Define a User struct with dynamically allocated fields✅
2. Write create/destroy functions for a struct✅
3. Pass structs by value vs pointer—measure difference✅
4. Implement a linked list node✅
5. Introduce and fix a dangling pointer bug✅

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MODULE 6 – File I/O & System Interaction

Goal: Work with the OS

Topics

• FILE*, fopen, fread, fwrite
• Binary vs text files
• Error handling with errno
• Resource leaks (files ≠ memory)

Exercises

1. Read a file line by line✅
2. Write a binary file and read it back
3. Implement a config file parser
4. Handle all failure cases explicitly
5. Intentionally forget fclose and detect it

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MODULE 7 – Undefined Behavior (DEEP DIVE)

Goal: Learn what C does not promise

Topics

• What UB actually is
• Strict aliasing
• Signed integer overflow
• Uninitialized reads
• Lifetime violations

Exercises

1. Write code that behaves differently with -O0 vs -O2
2. Trigger signed overflow
3. Use an uninitialized variable
4. Cast incompatible pointer types
5. Explain why behavior is undefined

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MODULE 8 – Advanced Memory & Performance

Goal: Think like a systems programmer

Topics

• Custom allocators
• Memory pools
• Cache friendliness
• Alignment
• restrict
• Escape analysis

Exercises

1. Write a simple arena allocator
2. Compare malloc vs arena performance
3. Implement a fixed-size object pool
4. Profile memory access patterns
5. Remove heap allocations from hot paths

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MODULE 9 – Concurrency (Low-Level)

Goal: Understand shared memory dangers

Topics

• pthread
• Data races
• Mutexes
• Atomic operations
• False sharing

Exercises

1. Write a multithreaded counter (broken)
2. Fix it with a mutex
3. Fix it with atomics
4. Cause a race condition intentionally
5. Analyze race with ThreadSanitizer

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MODULE 10 – Real-World C Projects

Goal: Prove mastery

Project Ideas

• Custom memory allocator
• HTTP server (no frameworks)
• JSON parser
• malloc replacement
• Simple shell

Requirements

• Zero memory leaks

• No undefined behavior

• Compiles with:

  -Wall -Wextra -Werror -fsanitize=address,undefined

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🔧 Tooling You MUST Use

gcc / clang
valgrind
AddressSanitizer
UndefinedBehaviorSanitizer
gdb

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🧠 Mindset Shift (Important)

From Node.js:

“The runtime protects me”

To C:

“The compiler trusts me—and will punish mistakes silently”

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📚 Recommended Resources

• Book: The C Programming Language – K&R
• Book: Expert C Programming – Peter van der Linden
• Book: Computer Systems: A Programmer’s Perspective
• Practice: LeetCode (but in C, memory-safe)

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