count days between two dates

count_days_between_dates.rb

# definition

# provide an optional day name (in English) 
# as the last parameter to get the number of times that day occurs
# between the two provided dates
#
# dates (t1 and t2) should be valid Time object dates
def list_days_between(t1, t2, day_name=nil)
    days = []
    (t2.to_i..t1.to_i).step(86400) do |t|
        days << Time.at(t).strftime('%A')
    end
    
    if day_name
        days.collect! { |d| d if d == day_name }
        days.delete_if {|d| d == nil}
        days = days.count
    end
    
    days
end

# use

now = Time.now

# according to Google: 10 000 000 seconds = 115.740741 days
# note: I make no claim about the efficiency of this algorithm... 
# improvement suggestions are welcome!
day_names_count = list_days_between(now, now-10000000, 'Saturday')
day_names = list_days_between(now, now-10000000)

puts 'Array of days: ' + day_names.inspect
puts 'Count of Saturdays: ' + day_names_count.inspect

puts 'Total days:' + day_names.count.to_s