Around about 20 years ago, I left my first job at Frontier Software after 2 years. All the code was in COBOL, and it was some of the best, cleanest code I’ve ever seen. For common code, we would just include libraries to reuse standard functions. I can remember reading the date routines and the obscure logic of the leap year calculations. These days, most languages provide standard libraries of functions, so all the hard work is done. Does this mean that programs all handle leap years now? Apparently not, in fact the situation is so poor that “The honor society of leap year day babies” has provided a code snippet for programmers to re-use. They acknowledge it isn’t the best, and it is just in perl, but they are not programmers just frustrated users (looking for programmers to provide other examples). They have actually updated the code and added a ruby version as well, but being unfamiliar with change control, the new version is hidden as a link off the old page. So what are some of the things that frustrated them? Systems that refuse to allow Feb 29 in a leap year as a birthday. A ToysRus birthday card system that won’t accept leap day birthdays, YouTube (since fixed), Nickelodeon and Pampers, and assorted government systems . The workaround is typically to force a choice of a day before or a day after, which is effectively corrupting the information. No wonder they are annoyed.