Question

I have a problem with an if condition that I want to use within a block. More precisely I want to get a string from an array, change that string and save it back to the array if a certain condition holds.

I have an array called “leuchtturmgesamtheit” which consists of strings.
Most of those strings look like this:

ACH-92941100

ACH-92941102

My aim is to aggregate those two strings. Thats why I want to rename the strings so that they have the same name. To do that I want to cut of the last character. After that I can use uniq! on the array.

Here is what I did:

leuchtturmgesamtheit.each { |replace|

  if replace.count("1234567890")==8
    replace=replace[0...-1]
  end

}

leuchtturmgesamtheit.uniq!

print leuchtturmgesamtheit

I expected to get:

ACH-9294110

But instead I get the same two strings back.

RubyMine tells me that the bold marked “replace” is a local variable not used after assignment. So the problem seems to be the if condition inside the block. What did I do wrong?

Answer 1

replace=replace[0...-1] is only changing which string the local variable within the block refers to and is not updating the entries in the array. There are a couple of solutions.

One is to use each_with_index and update the actual strings in the array:

e.g.

leuchtturmgesamtheit.each_with_index do |replace, index|
  if replace.count("1234567890") == 8
    leuchtturmgesamtheit[index] = replace[0...-1]
  end
end

another is to use map! to update the array e.g.

leuchtturmgesamtheit.map! do |entry|
  if entry.count("1234567890") == 8
    entry[0...-1]
  else
    entry
  end
end

---

steenslag’s answer is also good for scenarios where the string manipulation needed can be done on methods that modify the existing string, as is the case here.