Question

i have four dates:

First two are the beginning and end of a month

start_m = Time.new(2010,1).beginning_of_month
end_m = Time.new(2010,1).end_of_month

and the last two, d1 and d2, with d1 <= d2

What i want is an array containing the day numbers that come from the intersection of start_m -> end_m and d1->d2

for example:

start_m = 2011-01-01
end_m = 2011-01-31
d1 = 2010-12-20
d2 = 2011-01-11

the result would be

[1,2,3 ... 11]

is there an easy approach to do this intersection?

Answer 1

require 'date'

start_m = Date.parse('2011-01-01')
end_m = Date.parse('2011-01-31')
d1 = Date.parse('2010-12-20')
d2 = Date.parse('2011-01-11')

puts (start_m..end_m).to_a & (d1..d2).to_a

---

See documentation for Array#& . Output:

2011-01-01
2011-01-02
2011-01-03
2011-01-04
2011-01-05
2011-01-06
2011-01-07
2011-01-08
2011-01-09
2011-01-10
2011-01-11