Summing all numbers in an array

Question

I want to put a possibly infinite amount of numbers in and then it's added to an array, which is then all added together.

I saw this on a few other questions but they were all just puts-ing the array, not summing.

case input
 when 'add'
 puts "Enter the numbers to add on separate lines then hit enter on another line"
 add_array = []
 numbers_to_add = " "
 while numbers_to_add != ""
  numbers_to_add = gets.chomp
  add_array.push numbers_to_add
 end
 add_array.delete('')
 add_array.map(&:to_f).inject(:+)
 puts add_array
end

possible duplicate of [How to sum array of numbers in Ruby?](http://stackoverflow.com/questions/1538789/how-to-sum-array-of-numbers-in-ruby) — Mircea, Jun 30 '15 at 22:26

score 4 · Accepted Answer · edited Jun 30 '15 at 21:11

4

You can utilize the inject method.

[1,2,3].inject(:+) #=> 6

By the looks of your code I'd guess that your incoming array is an array of strings, not an array of numbers. To convert them to decimals (floats) you can use:

sum = add_array.map(&:to_f).inject(:+)
puts sum

This applies the #to_f operation on every element, then passes that to the summing function (#inject(:+))

edited Jun 30 '15 at 21:11

the Tin Man

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answered Jun 30 '15 at 20:13

PhilVarg

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Wait it's still not working. Dunno if it's my messing it up. I've edited the original post with the current code @PhilVarg – ThomasStringer Jun 30 '15 at 20:19
if your input is coming in as a string, you may need to convert each element `#to_i` or `#to_f`first – PhilVarg Jun 30 '15 at 20:20
can you post what `add_array` looks like? – PhilVarg Jun 30 '15 at 20:21
What in the console when running? @Phil – ThomasStringer Jun 30 '15 at 20:24
@CosmicRustle i've edited my response with the code that should work. note, that you have to reassign add_array to that value. – PhilVarg Jun 30 '15 at 20:29
Right I've edited the code. When I use `puts add_array.to_s` I get [ "5", "5" ] and nothing is added – ThomasStringer Jun 30 '15 at 20:32
Yes! Thankyou so much. Obviously a noob here but u helped a lot. I would've moved to chat but I don't even have enough points lol. Thanks – ThomasStringer Jun 30 '15 at 20:35
`map(&:to_f)` creates an unnecessary temporary array. Better to just `inject(0) { |t,e| t+e.to_f }`. You've only dealt with the easy part; the infinite-number case is the challenge. Please don't request upvoting and acceptance. It's unbecoming. – Cary Swoveland Jun 30 '15 at 21:23

Summing all numbers in an array

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