Question

Below is the code:

ruby-1.9.2-p290 :019 > "a, , b, c".delete(" , ") 
 => "abc"

I want it to be

a, b, c

What have I done wrong?

Answer 1

delete removes all characters occuring in the string you hand over to it (see ruby-doc). What you need is something like

"a, , b, c".gsub(/(\s*,\s*)+/, ', ')

UPDATE:

As mentioned in a comment below, the string is the result of a join(', '). In this case the better approach would be to remove the empty/nil elements before joining, i.e.

array.compact.join(', ')                      # if some elements are nil
array.delete_if(:&empty?).join(', ')          # if some elements are ''
array.compact.delete_if(:&empty?).join(', ')  # if both can occur