Some think that the dd-mm-yyyy date format is a logical format, because the elements are in order from smallest to biggest. I believe that it comes from the fact that the day changes most often, followed by the month, then year. Others may think that mm-dd-yyyy is a useful date format, because it comes from the fact that users of said format put the month first because they base their dates on how close a calendar date (the date omitting the year) is to another, i.e. New Years’, Halloween, Valentines’, etc.. It’s based on the yyyy-mm-dd format, but the year itself is irrelevant to the calendar date. The flaw with this date format (mm-dd-yyyy) is that the elements are not in order, which could very easily lead to it perplexing people not used to this date format. Therefore, this merits no further consideration. The two combatants for most logical date format are: yyyy-mm-dd and dd-mm-yyyy. In the next paragraph, I will explain in detail what the logic behind the formats is, and why the former is more logical.
The elements of the remaining date formats are in order, from largest to smallest, or vice versa. This is what they have in common in terms of the logic behind said formats are. Before I begin deciding which one is better, let’s take a look at place value notation, and how it pertains to this argument.
Take the number 765 for example (note that the radix this number is displayed in could be anything higher than 7). The ‘7’ represents 7 multiplied by the base to the second power, so 700. The ‘6’ represents 6 multiplied by the base, so 60. The ‘5’ simply represents 5. Add them all up (700+60+5) and the example number (765) is obtained. Place value notation is big-endian, meaning that it takes the digit that represented the highest quantity and placed it in the beginning. It then takes the digit with the next highest quantity and places it to the right of the digit representing the highest quantity. It goes on and on until the last digit.
Now that I have examined place value notation and used an example, let’s take a look at dd-mm-yyyy. While this format is little-endian, place value still applies in the elements, so the elements themselves are big-endian. The ordering of the elements is inconsistent with place-value notation. To visually clarify this problem, I have colored the digit representing the smallest quantity of the date format in blue, and the largest red: dd-mm-yyyy. Not so logical now, is it? Note that if the ‘dd’ element is 12 or less, the format could also very easily be interpreted as mm-dd-yyyy, and vice versa. This is a disadvantage that it has in common with the mm-dd-yyyy format.
Now let’s examine the yyyy-mm-dd format. Just like I did in the previous paragraph with the dd-mm-yyyy format, I will color the digit representing the smallest quantity in blue, and the digit representing the largest quantity red: yyyy-mm-dd. The digits in the elements are big-endian and the elements in the date format are also big-endian. The ordering of the elements is consistent with place-value notation.
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