Question

I am trying to parse a string 26/03/2012, in dd/mm/yyyy format to Ruby’s Date using Date.strptime, as follows:

#!/usr/bin/ruby
require 'date'
puts 'Ruby Version: ' + RUBY_VERSION
date_str = '26/03/2012'

date = Date.strptime(date_str, "%d/%m/%y")
puts 'Parsed Date: ' + date.to_s

The output is:

Ruby Version: 1.8.7
Parsed Date: 2020-03-26

The year part has become 2020, instead of 2012!

Answer 1

That should be %Y upper case, rather than %y:

date = Date.strptime(date_str, "%d/%m/%Y")
puts 'Parsed Date: ' + date.to_s
# Parsed Date: 2012-03-26

From the docs:

 Date (Year, Month, Day):
    %Y - Year with century (can be negative, 4 digits at least)
            -0001, 0000, 1995, 2009, 14292, etc.
    %C - year / 100 (round down.  20 in 2009)
    %y - year % 100 (00..99)

Since %y expects two digits only, it takes the first two 20 and assumes that to be a 2 digit representation of 2020, since 2020 % 100 = 20.