Quick C Preprocessor Cheat Sheet

[Reference] file and line

#define LOG(msg) console.log(__FILE__, __LINE__, msg)
#=> console.log("file.txt", 3, "hey")

[Reference] Stringification

#define STR(name) #name
char * a = STR(object);   #=> char * a = "object";

[Reference] Token concat

#define DST(name) name##_s name##_t
DST(object);   #=> object_s object_t;

[Reference] Macro

#define DEG(x) ((x) * 57.29)

[Reference] Error

#if VERSION == 2.0
  #error Unsupported
  #warning Not really supported
#endif

[Reference] If

#ifdef DEBUG
  console.log('hi');
#elif defined VERBOSE
  ...
#else
  ...
#endif

[Reference] Defines

#define FOO
#define FOO "hello"

#undef FOO

[Reference] Includes

#include "file"

[Reference] Compiling

$ cpp -P file > outfile

Reference

• C Preprocessor
• C Preprocessor Cheat Sheet