How to return the substring of a string between two strings in Ruby?

Question

How would I return the string between two string markers of a string in Ruby?

For example I have:

• input_string
• str1_marker

Answer 1

Here's some alternate ways to do what you want, that are how I'd go about it:

s = "Charges for the period 2012-01-28 00:00:00 to 2012-02-27 23:59:59:
\nAny Network Cap remaining: $366.550
International Cap remaining: $0.000"  # => "Charges for the period 2012-01-28 00:00:00 to 2012-02-27 23:59:59:
\nAny Network Cap remaining: $366.550
International Cap remaining: $0.000"

dt1, dt2 = /period (\S+ \S+) to (\S+ \S+):/.match(s).captures  # => ["2012-01-28 00:00:00", "2012-02-27 23:59:59"]
dt1                                                            # => "2012-01-28 00:00:00"
dt2                                                            # => "2012-02-27 23:59:59"

This is using "period" and "to" and the trailing ":" to mark the begin and end of the range to be searched for, and grabbing the non-whitespace characters that signify the date and time in each datetime stamp.

Alternately, using "named-captures" predefines the variables:

/period (?\S+ \S+) to (?\S+ \S+):/ =~ s  # => 16
dt1                                                # => "2012-01-28 00:00:00"
dt2                                                # => "2012-02-27 23:59:59"

From that point, if you want to break down the values returned you could parse them as dates:

require 'date'
d1 = DateTime.strptime(dt1, '%Y-%m-%d %H:%M:%S')  # => #
d1.month                                          # => 1
d1.day                                            # => 28

Or you could even use sub-captures:

matches = /period (?(?\S+) (?\S+)) to (?(?\S+) (?\S+)):/.match(s)
matches # => #
matches['dt1']   # => "2012-01-28 00:00:00"
matches['date1'] # => "2012-01-28"
matches['time2'] # => "23:59:59"

This is all documented in the Regexp documentation.