C Coding Standards

When reviewing or generating C code, follow these rules:

File Naming

• Source files: snake_case with .c extension (e.g., user_service.c, data_parser.c)
• Header files: snake_case with .h extension (e.g., user_service.h, data_parser.h)
• Keep names short but descriptive (max ~20 characters)

Header Guards

• Format: UPPER_SNAKE_CASE with _H suffix
• Include path in guard: (e.g., PROJECT_MODULE_FILE_H)

#ifndef USER_SERVICE_H
#define USER_SERVICE_H
// content
#endif /* USER_SERVICE_H */

Variable Naming

• Local variables: snake_case (e.g., user_count, buffer_size, is_valid)
• Global variables: snake_case with g_ prefix (e.g., g_config, g_instance_count)
• Static variables: snake_case with s_ prefix (e.g., s_initialized, s_cache)
• Pointers: Include p or ptr suffix when helpful (e.g., user_ptr, buffer_p)

Constant/Macro Naming

• Macros: UPPER_SNAKE_CASE (e.g., MAX_BUFFER_SIZE, DEFAULT_TIMEOUT)
• Enum values: UPPER_SNAKE_CASE (e.g., STATUS_OK, ERROR_INVALID_INPUT)
• Compile-time constants: UPPER_SNAKE_CASE with #define

Function Naming

• Functions: snake_case (e.g., calculate_total(), parse_input())
• Module prefix: Use module name prefix (e.g., user_create(), user_destroy())
• Static functions: snake_case, no prefix needed (internal to file)
• Init/cleanup pairs: Use _init() and _cleanup() or _create() and _destroy()

Type Naming

• Structs: snake_case with _t suffix or PascalCase (e.g., user_data_t or UserData)
• Typedefs: snake_case with _t suffix (e.g., user_id_t, callback_fn_t)
• Enums: snake_case with _e suffix for type (e.g., status_e)

Organization

• Header includes at top (system headers, then project headers)
• Macro definitions after includes
• Type definitions (structs, enums, typedefs)
• Function prototypes
• Global/static variable declarations
• Function implementations