I want to create my own time stamp data structure in C.
DAY ( 0 - 31 ), HOUR ( 0 - 23 ), MINUTE ( 0 - 59 )
What is the smallest data structure possible?
Well, you could pack it all in an
unsigned short (That's 2 bytes, 5 bits for Day, 5 bits for hour, 6 bits for minute)... and use some shifts and masking to get the values.
unsigned short timestamp = <some value>; // Bits: DDDDDHHHHHMMMMMM int day = (timestamp >> 11) & 0x1F; int hour = (timestamp >> 6) & 0x1F; int min = (timestamp) & 0x3F; unsigned short dup_timestamp = (short)((day << 11) | (hour << 6) | min);
or using macros
#define DAY(x) (((x) >> 11) & 0x1F) #define HOUR(x) (((x) >> 6) & 0x1F) #define MINUTE(x) ((x) & 0x3F) #define TIMESTAMP(d, h, m) ((((d) & 0x1F) << 11) | (((h) & 0x1F) << 6) | ((m) & 0x3F)
(You didn't mention month/year in your current version of the question, so I've omitted them).
unsigned short - not signed