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C Multi-file Projects - Professional Development Workflow
Master header files, compilation, and project organization like a professional developer
Learning Progress
Track your multi-file mastery journey
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Challenges Completed0/6
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Projects Built0
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Multi-file Concepts
Explore different aspects of C project organization
Project File Creator
Add new files to your library collection
Project Files
Your current library collection
C
main.c
Source file
1 deps
H
calculator.h
Header file
C
calculator.c
Source file
1 deps
Spaced Repetition Challenge System
Build long-term mastery through evidence-based learning
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beginner
Challenge 1 of 6
What's the main difference between header (.h) and source (.c) files?
How confident are you in your answer?
1=Guessing, 3=Somewhat sure, 5=Very confident
Project Files
Interactive C code with memory visualization
Concept Deep Dive
Understanding the library metaphor for code organization
Library Organization System
Headers are catalogs, sources are book collections
Header Files (.h)
📑 Function declarations
📑 Type definitions
📑 Constants
📑 "What is available"
Source Files (.c)
📚 Function implementations
📚 Actual code logic
📚 Private functions
📚 "How it works"
Multi-file Learning Journey0/5
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Professional Development Patterns
Real-world practices used by software teams
Team Collaboration Standards
• Consistent directory structure across projects
• Clear separation of public/private interfaces
• Comprehensive header documentation
• Automated build systems (Make, CMake, Bazel)
Professional Best Practices
• Header guards prevent inclusion disasters
• Forward declarations minimize dependencies
• Static functions encapsulate implementation details
• Const correctness shows intentionality
• Meaningful file/function naming conventions
Code Review Red Flags
• Implementations in header files (breaks encapsulation)
• Missing header guards (compilation time bombs)
• Circular includes (architectural problems)
• Global variables without extern declarations
• Platform-specific code not properly abstracted
Industry Examples
Linux Kernel: Massive multi-file project with strict organization
Game Engines: Modular architecture with clean interfaces
Embedded Systems: Hardware abstraction through headers
Libraries (libssl, zlib): Public API vs private implementation
Multi-file Debugging Guide
Turn errors into learning opportunities
"undefined reference to 'function_name'"
Cause: Linker can't find the function implementation
Fix: Include the .c file containing the function in your build command
Example:
Fix: Include the .c file containing the function in your build command
Example:
gcc main.c missing_file.c -o program"redefinition of 'symbol_name'"
Cause: Header included multiple times without guards
Fix: Add header guards:
Prevention: Always use header guards in .h files
Fix: Add header guards:
#ifndef HEADER_HPrevention: Always use header guards in .h files
"fatal error: 'file.h' file not found"
Cause: Compiler can't locate the header file
Fix: Check filename spelling and use correct include path
Tip: Use
Fix: Check filename spelling and use correct include path
Tip: Use
"file.h" for local, <file.h> for system headers"implicit declaration of function"
Cause: Function used before declaration/prototype
Fix: Include proper header file or add function prototype
Modern C: This is an error in C99+ (good!)
Fix: Include proper header file or add function prototype
Modern C: This is an error in C99+ (good!)
💡 Pro debugging tip: Read error messages from top to bottom - the first error often causes cascading errors below. Fix the first one first!