CODEWITHSUNDEEP
rubystringint
Logan
Logan

Reputation: 45

Array of integers from file

I am trying to grab large numbers from a file, store them as an array, and add them up.

nums = Array.new
x, total=0, 0
file = File.open("inputfile.txt", 'r')
while !file.eof?
  nums[x] = file.readline
  x+=1
end

while x>0
  x-=1
  total += nums[x]
end

puts total

When my code executes, I get an error saying:

String can't be coerced into Fixnum (TypeError)

I checked to make sure that each array element actually has the right data in it. I think that the numbers are considered strings when stored. If that's the case, how would I change the array to integers so I can total them up?

Upvotes: 3

Views: 1459

Answers (3)

the Tin Man
the Tin Man

Reputation: 160631

Here's how I'd do it:

total = 0
File.foreach("inputfile.txt") { |li| total += li.to_i }
puts total

Storing a large array in memory isn't a good idea because you can fill your available memory before your code can calculate a sum. Instead, read the file line-by-line and calculate as you go.

Benchmarks show that line-by-line I/O is as fast as reading an entire file into memory and then trying to process it as single lines, so use the more conservative IO.foreach or ios.each_line to avoid filling memory needlessly.

Upvotes: 1

FMc
FMc

Reputation: 42421

You can iterate line-by-line over an opened file:

total = File.open("inputfile.txt").inject(0) { |sum, line| sum + line.to_i }

Also see the example in the comment from squiguy, using map and reduce.

Upvotes: 1

snowingheart
snowingheart

Reputation: 120

Just modify 

nums[x] = file.readline

to

nums[x] = file.readline.to_i

Cheers!

Upvotes: 4

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