add Fixnum#digits, about 2x faster than Integer#digits

project_euler/lib/project_euler.rb

@@ -1,3 +1,4 @@
+require 'project_euler/core_extensions/fixnum'
 require 'project_euler/core_extensions/integer'
 require 'project_euler/core_extensions/array'
 require 'project_euler/core_extensions/enumerable'

project_euler/lib/project_euler/core_extensions/fixnum.rb

@@ -0,0 +1,10 @@
+class Fixnum
+  def digits
+    working_int, digits = self, Array.new
+    until working_int.zero?
+      digits.unshift working_int % 10
+      working_int /= 10
+    end
+    digits
+  end
+end

project_euler/spec/lib/core_extensions/fixnum_spec.rb

@@ -0,0 +1,13 @@
+require 'spec_helper'
+require 'project_euler/core_extensions/fixnum'
+
+describe Fixnum do  
+  describe '#digits' do
+    sample = [1,2,3,4,5,6,7,8,9,0] * 3
+    sample.each_index do |size|
+      crnt = sample.take(size.next)
+      next unless crnt.join.to_i.is_a? Fixnum
+      specify { crnt.join.to_i.digits.should == crnt }
+    end
+  end
+end