Ruby sum stdin integers

I have:

$ ruby -v
ruby 2.0.0p648 (2015-12-16 revision 53162) [universal.x86_64-darwin16]

      

        
        
        
      

    

Suppose you have a sequence of integers, a 1..n

ruby newbie sums up the sequence like this:

$ ruby -e 's=0
     for i in 1..500000
        s+=i
     end
     puts s'
125000250000

      

        
        
        
      

    

Now let's say I have the same sequence coming from stdin

:

$ seq 1 500000 | ruby -lne 'BEGIN{s=0}
                            s+=$_.to_i
                            END{puts s} '   
125000250000

      

        
        
        
      

    

So far so good.

Now increase the terminal value from 500,000 to 5,000,000:

$ ruby -e 's=0
         for i in 1..5000000
            s+=i
         end
         puts s'
12500002500000   <=== CORRECT

$ seq 1 5000000 | ruby -lne 'BEGIN{s=0}
                             s+=$_.to_i
                             END{puts s} '
500009500025     <=== WRONG!

      

        
        
        
      

    

He produces a different amount.

awk

and perl

give the correct result with the same sequence:

$ seq 1 5000000 | awk '{s+=$1} END{print s}'
12500002500000
$ seq 1 5000000 | perl -nle '$s+=$_; END{print $s}'
12500002500000

      

        
        
        
      

    

Why is the ruby ​​producing the wrong amount? I do not think it overflow, as awk

and perl

working properly on the same input.

Conclusions:

Thanks to David Aldridge for diagnosing this.

• OS X and BSD are seq
  
  converted to floating point output at 1,000,000, whereas GNU seq
  
  supports arbitrary precision integers. OS X is seq
  
  useless as a source of integers greater than 1,000,000. OS X example:

  $ seq  999999 1000002
  999999
  1e+06
  1e+06
  1e+06
  
        
  
          
          
          
        
  
      

• Method ruby .to_i
  
  noiselessly converts partial string to an integer, and in this case it is an error. Example:

  irb(main):002:0> '5e+06'.to_i
  #=> 5
  
        
  
          
          
          
        
  
      

• The "correct" line in the script is to use $_.to_f.to_i
  
  to use floats, or to use Integer($_)
  
  so that the script doesn't crash silently. awk
  
  and perl
  
  split 5e + 06 by float, ruby
  
  not implied:

  $ echo '5e+06' | awk '{print $1+0}'
  5000000
  $ echo '5e+06' | ruby -lne 'print $_.to_i+0'
  5
  
        
  
          
          
          
        
  
      

• And thanks to Stefan Schüßler for opening the rubi function request for behavior .to_i
  
  .