Change string in a date format to another format

Question

I have a string like this (YYYYMMDD):

20120225

And I want to have a string like this (MM/DD/YYYY):

02/25/

Answer 1

It's possible with regular expressions:

s1 = '20120225'
s2 = "$2/$3/$1" if s1 =~ /(\d{4})(\d{2})(\d{2})/

Or if you're sure of the format of your string and have performance issues, I think the best solution is

s2 = s1[4..5] + '/' + s1[6..7] + '/' + s1[0..3]

But if you have no performance needs, I think the solution of Andrew Marshall is better because it checks the date validity.