{0} is standard C. {} is currently a (common) compiler extension but will be standard C23: https://open-std.org/JTC1/SC22/WG14/www/docs/n2900.htm
#ifdef __cplusplus
# define ZERO_INIT {}
#else
# define ZERO_INIT {0}
#endif
Works for arrays, aggregates, scalars, etc., but I just use it for arrays and aggregates: `char buf[32] = ZERO_INIT; struct X x = ZERO_INIT;`