Question

Given an array of DateTime Strings, I want to just fetch the times e.g. 10:30:00.
So far I come up with this, but it wont give me the right result:

["2011-07-30 10:00:00","2011-07-30 12:00:00"].each{|item| item.match(/\d{2}:\d{2}:\d{2}/)}

Answer 1

If all the strings really are like that then just do some substring mangling:

a     = ["2011-07-30 10:00:00","2011-07-30 12:00:00"]
times = a.map { |e| e[11,8] }

This will also work if your timestamps include things like 2011-07-30 10:00:00.1123, 2011-07-30T10:00:00, or 2011-07-30 10:00:00 +0700.

If you wanted to be friendlier to the future, then you could do this:

off   = '9999-99-99 '.length
len   = '99:99:99'.length
times = a.map { |e| e[off, len] }

so no one would have to guess what the 11 and 8 were all about.