Question

I’m using Ruby, and I want to write a function that takes a delimited string str (delimited by //), and returns the final part of the string, that is, the part after the last // in the string. For example, given a//b///cd, it should return cd.

Can I use a regular expression to do this, and if so, what expression should I use?

Answer 1

As Nhahtdh wrote in his comment you can use /.*\/\/(.*)/

Which in Ruby, would be something like

regex = %r{.*               # any character (0 up to infinit-times) till we find the last
           //               # two consecutive characters '/'
           (?<last_part>.*) # any character (0 up to infinit-times)
          }
string = 'a//b///cd'

puts regex.match(string)[:last_part]
#=> cd

You can find about the %r in the RegularExpression section of the ProgrammingRuby.