#!/usr/bin/env ruby
# code by fre3vil






p "string ring".tr('r', 'g') # retuen a copy string 'r' to 'g'

p "string ring".sub('r', 'g') # only replace the first match character. 'r' to 'g'

p "string ring".gsub('r', 'g') # replace all 'r' to 'g'

