C Interfaces and Implementations Mastery - Expanded Project Guides
Generated from:
C_INTERFACES_AND_IMPLEMENTATIONS_MASTERY.md
Overview
Master the art of building bulletproof, reusable C libraries through David Hanson’s disciplined interface-based programming methodology. This series of 20 projects takes you from foundational modules (assertions, memory management) through sophisticated data structures (hash tables, sets, bit vectors) to advanced topics (arbitrary precision arithmetic, cooperative threading).
By completing these projects, you’ll understand why separating interface from implementation creates maintainable code, how to design APIs that are impossible to misuse, and how to build a complete ecosystem of data structures and utilities that work together seamlessly.
Project Index
| # | Project | Difficulty | Time | Key Focus |
|---|---|---|---|---|
| 1 | Assert Module | Intermediate | 1-2 days | Fail-fast philosophy, preprocessor macros |
| 2 | Mem Module | Advanced | 3-5 days | Checked allocation, leak detection |
| 3 | Arena Module | Advanced | 3-5 days | Memory pools, bulk allocation |
| 4 | Atom Module | Intermediate | 2-3 days | String interning, hash tables |
| 5 | Except Module | Advanced | 3-5 days | setjmp/longjmp, exception handling |
| 6 | List Module | Intermediate | 2-3 days | Functional linked lists, immutability |
| 7 | Table Module | Advanced | 3-5 days | Generic hash tables, function pointers |
| 8 | Set Module | Advanced | 3-5 days | Mathematical sets, hash-based lookup |
| 9 | Array Module | Intermediate | 2-3 days | Dynamic arrays, bounds checking |
| 10 | Seq Module | Intermediate | 2-3 days | Double-ended queues |
| 11 | Ring Module | Intermediate | 2-3 days | Circular buffers, fixed-size containers |
| 12 | Bit Module | Advanced | 3-5 days | Bit vectors, compact boolean sets |
| 13 | Fmt Module | Advanced | 5-7 days | Extensible printf, variadic functions |
| 14 | Str Module | Intermediate | 2-3 days | Low-level strings, pointer arithmetic |
| 15 | Text Module | Advanced | 3-5 days | High-level immutable strings |
| 16 | XP Module | Expert | 5-7 days | Extended precision unsigned arithmetic |
| 17 | AP Module | Expert | 5-7 days | Arbitrary precision signed integers |
| 18 | MP Module | Expert | 5-7 days | Fixed-width large integers |
| 19 | Thread Module | Expert | 5-7 days | Cooperative threading, coroutines |
| 20 | Integration: Mini Standard Library | Expert | 2-3 weeks | Complete library, testing, documentation |
Learning Paths
Path 1: The Foundations Builder (4 weeks)
For developers who want the core patterns without every module.
Week 1: Assert → Mem → Arena
Week 2: Atom → Except
Week 3: List → Table
Week 4: Set → Build a mini-project using all modules
Projects: P01 → P02 → P03 → P04 → P05 → P06 → P07 → P08
You’ll have: Core patterns, 8 modules, ability to build real libraries
Path 2: The Data Structures Focus (6 weeks)
For developers who want to implement serious container libraries.
Week 1: Assert → Mem
Week 2: Atom → List (functional linked lists)
Week 3: Table (hash tables) → Set (set operations)
Week 4: Array (dynamic arrays) → Seq (deques)
Week 5: Ring (circular buffers) → Bit (bit vectors)
Week 6: Integration project
Projects: P01 → P02 → P04 → P06 → P07 → P08 → P09 → P10 → P11 → P12 → P20
You’ll have: 11 modules, complete container library, real implementation experience
Path 3: The Completionist (10-12 weeks)
For developers who want to master every module and the philosophy deeply.
Weeks 1-2: Foundation (Assert, Mem, Arena, Atom, Except)
Weeks 3-4: Data Structures I (List, Table, Set)
Weeks 5-6: Data Structures II (Array, Seq, Ring, Bit)
Weeks 7-8: Strings (Fmt, Str, Text)
Weeks 9-10: Arithmetic (XP, AP, MP)
Week 11: Threading (Thread module)
Week 12: Capstone: Mini Standard Library
Projects: All 20 in sequence
You’ll have: All 20 modules, deep understanding of C library design
Prerequisites
Essential Prerequisites
| Skill | What You Need | How to Verify |
|---|---|---|
| C Fundamentals | Pointers, pointer arithmetic, structs, unions | Can you implement a linked list from scratch? |
| Memory Model | Stack vs heap, malloc/free lifecycle | Can you explain where a local variable lives vs a malloc’d buffer? |
| Header Files | #include, header guards, declarations vs definitions | Can you explain why you get “multiple definition” errors? |
| Build Process | Compile vs link, .o files, static libraries | Can you build a project with multiple .c files using make? |
| Data Structures | Linked lists, hash tables, trees (conceptually) | Do you understand O(1) vs O(n) lookup? |
Development Environment
Required Tools
──────────────
□ C Compiler: GCC (gcc) or Clang (clang)
- Need: C11 support minimum (-std=c11)
□ Build System: Make (GNU Make preferred)
□ Memory Debugger: Valgrind (Linux) or AddressSanitizer
- Linux: valgrind --leak-check=full ./your_program
- macOS: clang -fsanitize=address -g your_code.c
□ Debugger: GDB (Linux) or LLDB (macOS)
Recommended Compiler Flags
──────────────────────────
CFLAGS = -Wall -Wextra -Wpedantic -std=c11 -g -O2
For development:
CFLAGS += -fsanitize=address -fsanitize=undefined
For production:
CFLAGS += -O3 -DNDEBUG
Key Resources
Primary Text
“C Interfaces and Implementations” by David R. Hanson - The book these projects are based on
Supporting Books
| Topic | Book | Relevance |
|---|---|---|
| C Fundamentals | “The C Programming Language” (K&R) | Foundation for everything |
| Modern C | “Effective C” by Robert C. Seacord | Best practices |
| Deep C | “Expert C Programming” by van der Linden | Understanding quirks |
| Systems Context | “Computer Systems: A Programmer’s Perspective” | How C maps to hardware |
Online Resources
| Resource | URL |
|---|---|
| CII Source Code | https://github.com/drh/cii |
| Hanson’s Home Page | https://www.cs.princeton.edu/~drh/ |
| Redis Internals | https://redis.io/docs/reference/internals/ |
| SQLite Architecture | https://sqlite.org/arch.html |
Core Concepts
These patterns appear throughout all 20 projects:
1. Opaque Types (Information Hiding)
// Header: Client sees only the pointer type
typedef struct Table_T *Table_T;
// Implementation: Only the .c file knows the structure
struct Table_T {
int size;
struct binding **buckets;
// ...
};
2. Checked Runtime Errors
void Table_put(Table_T table, void *key, void *value) {
assert(table); // Crash immediately if precondition violated
assert(key);
// ...
}
3. Naming Conventions
Module_T - The type (Table_T, List_T, Set_T)
Module_new - Constructor
Module_free - Destructor (takes T* to NULL the pointer)
Module_verb - Operations (Table_put, List_push, Set_member)
4. Polymorphism via Function Pointers
Table_T Table_new(int hint,
int cmp(const void *x, const void *y), // Compare function
unsigned hash(const void *key)); // Hash function
// Usage with different key types
Table_T string_table = Table_new(100, string_cmp, string_hash);
Table_T int_table = Table_new(100, int_cmp, int_hash);
Module Dependencies
Assert
│
┌───────┼───────┐
│ │ │
▼ ▼ ▼
Except Mem Atom
│ │
└───┬───┘
│
▼
Arena
│
┌─────────────┼─────────────┐
│ │ │
▼ ▼ ▼
List Table Set
│ │ │
└──────┬──────┴──────┬──────┘
│ │
▼ ▼
Array Seq
│ │
└──────┬──────┘
│
┌──────┴──────┐
│ │
▼ ▼
Ring Bit
│ │
└──────┬──────┘
│
┌──────┴──────┐
│ │
▼ ▼
Fmt Str
│ │
└──────┬──────┘
│
▼
Text
│
┌──────┴──────┐
│ │
▼ ▼
XP MP
│ │
└──────┬──────┘
│
▼
AP
│
▼
Thread
│
▼
Integration Project
Last updated: 2025-12-29