in reply to RE: Calculating a persons age based on their birthday.
in thread Calculating a persons age based on their birthday.

If you want to be slightly more accurate (not that this matters for another 100 years, but hey!) the leap year formula is that a leap year is divisable by 4, but not 100 (except if divisable by 400). Of course, the amount of error induced by leap years wouldn't effect your program unless the person was over a thousand years old (one day of error every four years would take a long time to become relevant), otherwise its safe to just div by 365.

Article about leap years.

  • Comment on RE: RE: Calculating a persons age based on their birthday.

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RE: RE: RE: Calculating a persons age based on their birthday.
by Adam (Vicar) on May 04, 2000 at 02:59 UTC
    I'm not sure how clear I was in the previous post. I was rather tired and stuff. The original question was:

    I need to calculate someone's age based on their birthday. The birthday is being pulled from MySQL so I have the FROM_DAYS() function which will give me the number of days they have been alive. I cannot just divide by 365 because of leap years and all. Any advice on accurately calculating someone's age?

    So I was trying to say that leap years are irrelevant. You have the birth date. So you just divide the number of days by 365. This will be off by one day every four years, meaning that their birthday will appear to creep at the rate of 6 hours a year. This shouldn't be a big deal though... it just means that their birthday will move forward a day every four years. This means that if a person enters a birth date for an age verification system, it would let them by 4 days before their 18th birthday or 5 days before their 21st. In almost any other application, the error is negligable.
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