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Ruby

Posted by ogechi1
ogechi1
14,455 Points

Ruby, print even numbers of array

I was doing a simple exercise to output the even numbers in an array. I tried to use a Ruby inline conditional 

my_array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Why does this statement work:

my_array.each { |value| puts value if value.to_f%2==0}

but not this one:

my_array.each { |value| puts value if !(value.to_f%2) }

Thanks in advance! Ogechi

1 Answer

Maciej Czuchnowski
Maciej Czuchnowski
36,441 Points

This:

my_array.each { |value| puts value if value.to_f%2==0}

works, because it is looking for a specific value - 0.

0 is not a falsy value in Ruby:

http://codequizzes.wordpress.com/2013/09/29/truthy-and-falsey-in-ruby/

Although it is in some languages, such as JavaScript:

http://designpepper.com/blog/drips/truthy-and-falsy-values-in-javascript.html

So your expression:

my_array.each { |value| puts value if !(value.to_f%2) }

Always gets false in the if statement, because it always gets a truthy value (including 0) and makes the opposite using the ! sign, so it ALWAYS returns false. Hope this helps.

ogechi1
ogechi1
14,455 Points

Hi Maciej, Thank you so much for shedding light on the problem! Much appreciated, :) Best, Ogechi