Days in month

[Dan Fitzpatrick]

Is there a method of Date or Time that gives the number of days in a
date's month or the last day of the month like:

d = Date.new(2005,4,20)
d.days_in_month #-> 30
#or
d.last_day_of_month #-> 30

Thanks,

Dan

 

[David A. Black]

Hi --

Is there a method of Date or Time that gives the number of days in a date's
month or the last day of the month like:

d = Date.new(2005,4,20)
d.days_in_month #-> 30
#or
d.last_day_of_month #-> 30

Funny you should ask

This came up on IRC a month or two ago, and the answer appears to be
no. So I wrote one:

# Date.dim -- days in month

require 'date'

class Date
def dim
d,m,y = mday,month,year
d += 1 while Date.valid_civil?(y,m,d)
d - 1
end
end

if __FILE__ == $0
puts (Date.today >> 1).dim
puts (Date.today << 1).dim
puts (Date.new(2004,2)).dim
end

__END__


David

 

[jc]

class Date
def days_in_month
((Date.new(year, month, 1) >> 1)-1).day
end
end

d = Date.new(2005,4,20)
puts d.days_in_month #-> 30

 

[Dan Fitzpatrick]

JC,

Thanks for the simple solution.

Dan

 

[Brian Buckley]

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!!! Yowser!

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[Ken Kunz]

Nice! Here's a slight variation that's even simpler:

class Date
def days_in_month
Date.civil(year, month, -1).day
end
end

 

[Ara.T.Howard]

Is there a method of Date or Time that gives the number of days in a date's
month or the last day of the month like:

d = Date.new(2005,4,20)
d.days_in_month #-> 30
#or
d.last_day_of_month #-> 30

from the excellent impl in the 'days of month' thread earlier this week:

harp:~ > cat a.rb
require 'date'

class Date
def days_in_month
self::class.civil(year, month, -1).day
end
alias dim days_in_month
def weekdays
(1..dim).to_a
end
end

p Date::new(2005, 02).weekdays
p Date::new(2005, 12).weekdays

harp:~ > ruby a.rb
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31]

harp:~ > cal 2 2005
February 2005
Su Mo Tu We Th Fr Sa
1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28

harp:~ > cal 12 2005
December 2005
Su Mo Tu We Th Fr Sa
1 2 3
4 5 6 7 8 9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30 31

boy i love ruby.

cheers.

-a
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