Question

I have this small snipped of code.

I don’t know ruby and I think this is a great opportunity to apply it.

I want to print all the lines in file e which are not in file c. Each line is a number.

This is what I’ve got:

 e = File.new('e').readlines
 c = File.new('c').readlines

 x = e.collect do |item|
   c.include?( item ) ? "" : item
 end

 p x.sort

The problem is that both file may have empty spaces and for that reason the same number may not be considered as such. ( eg. “1234 ” is different from ” 1234 ” )

What do I need in my code to fix it? I’ve tried c.include?(item.strip) .. .but doesn’t seems to work.

Answer 1

Perhaps doing the strip when you do the readlines would help, i.e.

e = File.readlines('e').map{|x| x.strip}
c = File.readlines('c').map{|x| x.strip}

Then you could use collect as you did, or perhaps select if you don’t want the empty strings:

x = e.select{|i| !c.include?(i)}

Edit: or as Benno suggests, use

x = e-c