I chose    #define SECONDS_PER_YEAR (60 * 60 * 24 * 365)
instead of #define SECONDS_PER_YEAR (60 * 60 * 24 * 365UL)<p>I realised that 365UL would make 16-bit machines happy. I haven't worked on such one from a long time.<p>I also make a mistake on int (*a)[10], and I had no idea about "volatile const".