Loop through an array while summing the output

Question

I am trying to use a for loop and then sum all of the outputs. I know this is a basic question, but I am not sure if I should be trying to solve this within the loop or using another array.

For example:

for i in 1..100
if foo / 2 == 0
#find the sum of all outputs
end

end

Answer 1

Try this:

(2..100).step(2).inject(:+) #=> 2550

Or:

2.step(100,2).inject(:+) #=> 2550

You can use sum instead of inject(:+) from Ruby 2.4+

Answer 2

I'm not entirely sure what you're asking, but my initial understanding is that you want to sum all of the numbers in a range (1..100) that meet a specific condition. In this case, something divided by 2 cannot equal zero aside from zero itself. I'm wondering if you meant %2, in which case, you're asking to sum all the even numbers in the range 1..100. This can be accomplished by doing the following.

    (1..100).select {|x| x if x.even?}.reduce(:+) 

Effectively, you want to enumerate over a range and select only the numbers that meet your condition, as specified in the block. Calling reduce and passing it an accumulator.