How to eliminate letter?

Question

I want a string which eliminates every "x, X". For example Xylophone -> ylophone, Xbox -> bo. This is my recent code:

class String
 def xaway
 s = self.split("")
 return ( s - ["xX"] ).join
 end
end

What is wrong?

Answer 1

What is wrong?

Splitting the string by "" returns an array of characters, e.g.:

"Xbox".split("")
#=> ["X", "b", "o", "x"]

And Array#- expects an array of elements to remove. But if you pass ["Xx"] it tries to remove the element "Xx" which doesn't exist in the array:

["X", "b", "o", "x"] - ["Xx"]
#=> ["X", "b", "o", "x"]

What you want is ["X", "x"]:

["X", "b", "o", "x"] - ["X", "x"]
#=> ["b", "o"]

The whole code:

class String
  def xaway
     (split("") - ["X", "x"]).join
  end
end

A little more concise:

class String
  def xaway
     (chars - %w[X x]).join
  end
end

Or, using String#delete:

class String
  def xaway
    delete("Xx")
  end
end

Note that you shouldn't modify Ruby's core classes.

Answer 2

You might be better off using the tr function, depending on your usage requirements:

class String
  def xaway
    tr("xX","")
  end
end