is a qute dog
#define

Pro tip: to save space in your C code, put the following in a common system header:

#define struct union

#define free(p) realloc(p, sizeof(int))

happiness and good fortune will be yours but only if you add this line to the most included header file in your very oldest and most inscrutable codebase at work within the next 20 seconds

#define if(...) if(!(__VA_ARGS__))

I feel like I'm the only C programmer on earth who prefers enums to #define's all over the place.

#define 2 1<<1

think carefully about the implications of this one

@typhlosion You joke but I had a coworker on a many-million-dollar shipping project show me a header with
#define void int
at the top and
#undef void
at the bottom 🤔

@typhlosion #define QBERT_WAS_HERE "#$%&*@!"

#define false true
#define private public
#define 0 -1
#define printf(...) printf("All work and no play makes Jack a dull boy\n")

#define virtual EMIT WARNING C4005