this post was submitted on 31 Oct 2024
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Just divide the number into its prime factors and then check if one of them is 2.
I remember coding actionscript in Flash and using modulo (%) to determine if a number was even or odd. It returns the remainder of the number divided by 2 and if it equals anything other than 0 then the number is odd.
Yeah. The joke is that this is the obvious solution always used in practise, but the programmer is that bad that they don't know it and use some ridiculous alternative solutions instead.
I believe that's the proper way to do it.
or divide the number by two and if the remainder is greater than
but less than
then
What if the remainder is greater than the first, but not less than the latter?
Like, for example, 1?
Then you should return false, unless the remainder is also greater than or equal to the twenty second root of 4194304. Note, that I've only checked up to 4194304 to make sure this works, so if you need bigger numbers, you'll have to validate on your own.
i hate to bring this up, but we also need a separate function for negative numbers
You can just bitwise AND those with ...000000001 (for however many bits are in your number). If the result is 0, then the number is even, and if it's 1, then the number is odd. This works for negative numbers because it discards the negative signing bit.