How to remove all non-digits from a string in ruby?

Question

Users input numbers in the following forms:

1-800-432-4567 800-432-4567 800.432.4566 (800)432.4567 +1(800)-432-4567 800 432 4567 

I want all of these to be turned into a stripped version without the special characters like 18004324567. The data come in the form of a String, so string checking isn't required.

My method is as below:

def canonical_form number   a = remove_whitespaces number #to clear all whitespaces in between   a.gsub(/[()-+.]/,'')      end  def remove_whitespaces number   number.gsub(/\s+/,'')  #removes all whitespaces end 

Is there a better way to do this? Can the white space check with the regular expression in canonical_form method be performed without having an extra method for white spaces? How can this be refactored or done in a neater way?

Answer 1

If the first argument of the tr method of String starts with ^, then it denotes all characters except those listed.

def canonical_form str   str.tr('^0-9', '')    end