this post was submitted on 07 Dec 2023
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Programming Horror

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God I wish there was an easier way to do this (programming.dev)
submitted 11 months ago* (last edited 11 months ago) by andioop to c/programming_horror
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[–] recursive_recursion 9 points 11 months ago* (last edited 11 months ago) (15 children)

modulo

pseudocode:

if number % 2 == 0
  return "number is even" (is_num_even = 1 or true)
else
  return "number is odd" (is_num_even = 0 or false)

plus you'd want an input validation beforehand

[–] mac 23 points 11 months ago* (last edited 11 months ago) (2 children)

who needs modulo when you can get less characters out of

while (number > 1) {
  number -= 2;
}
return number;

very efficient

edit: or theres the trusty iseven api

[–] nullPointer 9 points 11 months ago (2 children)

here is somewhat less:

return (number % 2) == 0;

[–] [email protected] 10 points 11 months ago (1 children)

return !(number & 1);

[–] [email protected] 8 points 11 months ago* (last edited 11 months ago) (1 children)

This is the way. Modulo takes too long to compute, bitwise compare should be a lot faster.

return !(number & 0x1);
[–] recursive_recursion 5 points 11 months ago* (last edited 11 months ago)

oh shit yo

this comment chain is pretty awesome, I learned a lot from this thanks!

[–] [email protected] 4 points 11 months ago

just check the last bit jesus christ, what is it with these expensive modulo operations?!

return !(n&1);

[–] [email protected] 2 points 11 months ago (1 children)

are the negative numbers all even?

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