[newbie] this month, the next month, and the one after that

[Mason Kessinger]

What I want to do is simple.

I'd like code that prints out the name of this month (January) the next
month (February) and the one after that (March)

I've been able to print this month:

<% t = Time.now %>
<%= t.strftime(" This Month is: %B") %>

But I can't figure out how to get the next months to print out!

 

[Jonathan Leighton]

What I want to do is simple.

I'd like code that prints out the name of this month (January) the next
month (February) and the one after that (March)

I've been able to print this month:

<% t = Time.now %>
<%= t.strftime(" This Month is: %B") %>

But I can't figure out how to get the next months to print out!

Well you'd add the month, expressed in seconds, to the current time.
That would be:

irb(main):001:0> puts (Time.now + 60 * 60 * 24 * 30).strftime("Next
month is %B")
Next month is February
=> nil

(Assuming a month is thirty days)

You are probably using Rails (I assume), so you can do this instead:

irb(main):002:0> require_gem 'activerecord'
=> true
irb(main):003:0> puts (Time.now + 1.month).strftime("Next month is %B")
Next month is February
=> nil

Again, that assumes a month is thirty days. A more reliable way would be
to find the next month, work out its length in seconds (precisely), and
then add it to Time.now.

Jon

 

[David Vallner]

What I want to do is simple.

I'd like code that prints out the name of this month (January) the next
month (February) and the one after that (March)

I've been able to print this month:

<% t =3D Time.now %>
<%=3D t.strftime(" This Month is: %B") %>

But I can't figure out how to get the next months to print out!

My first guess would be requiring "datetime", and then looking up the =20
month name per DateTime::MONTHNAMES[t.month + 1].

Mind you, DateTime::MONTHNAMES is one-indexed, starting from January, so =
=20
you'll have to do some index-shiftingto wrap around the end of the array =
=20
correctly. And since there's very little I hate more than shifting array =
=20
indices around, the exercise is left to the reader ;P

When I think about it, DateTime::MONTHNAMES[1..12][t.month % 12] should =20
work perfectly for the next month, with (t.month + 1) for the one after =20
that, etc.

David Vallner

 

[David Vallner]

Am Dienstag, den 17.01.2006, 04:45 +0900 schrieb Mason Kessinger:

Try this:

irb(main):040:0* t =3D Time.now
=3D> Mon Jan 16 21:27:58 CET 2006
irb(main):041:0> m =3D t.mon
=3D> 1
irb(main):042:0> nt =3D Time.mktime 2006, m + 1
=3D> Wed Feb 01 00:00:00 CET 2006
irb(main):043:0> p nt.strftime("%B")
"February"
=3D> nil
irb(main):044:0> nt =3D Time.mktime 2006, m + 2
=3D> Wed Mar 01 00:00:00 CET 2006
irb(main):045:0> p nt.strftime("%B")
"March"
=3D> nil


Cheers
detlef

Time#mktime. D'oh. I feel so dense for not remembering that one.

David Vallner

 

[James Edward Gray II]

Mind you, DateTime::MONTHNAMES is one-indexed, starting from January,

We can fix that.

so you'll have to do some index-shiftingto wrap around the end of
the array correctly. And since there's very little I hate more than
shifting array indices around, the exercise is left to the reader ;P

Okay, I'll bite:
=> ["January", "February", "March", "April", "May", "June", "July",
"August", "September", "October", "November", "December", "January",
"February", "March", "April", "May", "June", "July", "August",
"September", "October", "November", "December"]

three_months = months[months.index(current), 3]

=> ["January", "February", "March"]

James Edward Gray II

 

[ako...]

a little off-topic, but a related question: does ruby have support for
date/currency/number localisation? e.g. using comma instead of a dot in
real numbers, month/day names in languages other than english,
localised date format, etc?

thanks
konstantin

 

[Detlef Reichl]

Am Dienstag, den 17.01.2006, 05:55 +0900 schrieb James Edward Gray II:

Mind you, DateTime::MONTHNAMES is one-indexed, starting from January,

We can fix that.

so you'll have to do some index-shiftingto wrap around the end of
the array correctly. And since there's very little I hate more than
shifting array indices around, the exercise is left to the reader ;P

Okay, I'll bite:
=> ["January", "February", "March", "April", "May", "June", "July",
"August", "September", "October", "November", "December", "January",
"February", "March", "April", "May", "June", "July", "August",
"September", "October", "November", "December"]

three_months = months[months.index(current), 3]

=> ["January", "February", "March"]

i don't like redundant data...


irb(main):042:0* current = Time.now.mon
=> 1
irb(main):043:0> require "date"
=> false
irb(main):044:0> months = Date::MONTHNAMES.compact
=> ["January", "February", "March", "April", "May", "June", "July",
"August", "September", "October", "November", "December"]
irb(main):045:0> three_month = []
=> []
irb(main):046:0> (0..2).each {|i| three_month << months[(i+current-1) %
12]}
=> 0..2
irb(main):047:0> p three_month
["January", "February", "March"]
=> nil

detlef

 

[David Vallner]

Mind you, DateTime::MONTHNAMES is one-indexed, starting from January,

We can fix that.

so you'll have to do some index-shiftingto wrap around the end of the = =20
array correctly. And since there's very little I hate more than =20
shifting array indices around, the exercise is left to the reader ;P

Okay, I'll bite:
=3D> ["January", "February", "March", "April", "May", "June", "July", =20
"August", "September", "October", "November", "December", "January", =20
"February", "March", "April", "May", "June", "July", "August", =20
"September", "October", "November", "December"]

three_months =3D months[months.index(current), 3]

=3D> ["January", "February", "March"]

James Edward Gray II

Ye gods, that's so idiot-proof it ain't pretty anymore amd I let my brain=
=20
spin around index shifts.. I've been doing WAAAY too much Java at work. =20
Help, my 1337 R=FCby h@xx0r skills are disappearing! *sic*

David Vallner

 

[Kero]

What I want to do is simple.

I'd like code that prints out the name of this month (January) the next
month (February) and the one after that (March)

I've been able to print this month:

<% t = Time.now %>
<%= t.strftime(" This Month is: %B") %>

But I can't figure out how to get the next months to print out!

I can't find out how to print dates, but I do know how to get the next month
without all the assuming-30-days mess.

require 'date'
Date.today.to_s
(Date.today >> 1).to_s
=> "2006-02-16"
(Date.today >> 2).to_s
=> "2006-03-16"

 

[ara.t.howard]

Try this:

irb(main):040:0* t = Time.now
=> Mon Jan 16 21:27:58 CET 2006
irb(main):041:0> m = t.mon
=> 1
irb(main):042:0> nt = Time.mktime 2006, m + 1
=> Wed Feb 01 00:00:00 CET 2006
irb(main):043:0> p nt.strftime("%B")
"February"
=> nil
irb(main):044:0> nt = Time.mktime 2006, m + 2
=> Wed Mar 01 00:00:00 CET 2006
irb(main):045:0> p nt.strftime("%B")
"March"
=> nil

but

harp:~ > ruby -e' p(Time::mktime(2006,13)) '
-e:1:in `mktime': argument out of range (ArgumentError)
from -e:1


i prefer the stupid approach:

harp:~ > cat a.rb
class Time
def this_month
strftime '%b'
end
def next_month n = 1
t = dup
s = 60 * 60 * 24
n.times{ m = t.month; t += s until t.month != m }
t.strftime '%b'
end
end

t = Time::mktime 2006, 12
p t.this_month
p t.next_month
p t.next_month(2)


harp:~ > ruby a.rb
"Dec"
"Jan"
"Feb"


regards.

-a

 

[ara.t.howard]

Mind you, DateTime::MONTHNAMES is one-indexed, starting from January,

We can fix that.

so you'll have to do some index-shiftingto wrap around the end of the array
correctly. And since there's very little I hate more than shifting array
indices around, the exercise is left to the reader ;P

Okay, I'll bite:
=> ["January", "February", "March", "April", "May", "June", "July", "August",
"September", "October", "November", "December", "January", "February",
"March", "April", "May", "June", "July", "August", "September", "October",
"November", "December"]

three_months = months[months.index(current), 3]

=> ["January", "February", "March"]

but

irb(main):005:0> months[months.index(current), 42].size
=> 24

not good if the app is a mortage calculator! ;-)

-a

 

[Detlef Reichl]

Am Dienstag, den 17.01.2006, 07:06 +0900 schrieb (e-mail address removed):

On Tue, 17 Jan 2006, Detlef Reichl wrote:
=20
=20
but
=20
harp:~ > ruby -e' p(Time::mktime(2006,13)) '
-e:1:in `mktime': argument out of range (ArgumentError)
from -e:1
=20
=20

OK

=E2=98=BA: p(Time::mktime(2006,(13%12)))
Sun Jan 01 00:00:00 CET 2006

i prefer the stupid approach:
=20
harp:~ > cat a.rb
class Time
def this_month
strftime '%b'
end
def next_month n =3D 1
t =3D dup
s =3D 60 * 60 * 24
n.times{ m =3D t.month; t +=3D s until t.month !=3D m }

Outch found no good logic? who cares, lets do it with brute force

 

[ara.t.howard]

OK

=E2=98=BA: p(Time::mktime(2006,(13%12)))
Sun Jan 01 00:00:00 CET 2006

harp:~ > irb
irb(main):001:0> p(Time::mktime(2006,(48%12)))
ArgumentError: argument out of range
from (irb):1:in `mktime'
from (irb):1


you need

t =3D Time::now
n =3D 48
n =3D (t.month + n) % 12
(n =3D=3D 0 ? t : Time::mktime(1970, n)).strftime('%b')

sorry, couldn't resist! ;-)

Outch found no good logic? who cares, lets do it with brute force

hey! i said it was stupid ;-)

cheers.

-a
--=20
strong and healthy, who thinks of sickness until it strikes like lightning?
preoccupied with the world, who thinks of death, until it arrives like
thunder? -- milarepa

 

[A LeDonne]

Am Dienstag, den 17.01.2006, 04:45 +0900 schrieb Mason Kessinger:

Try this:

irb(main):040:0* t =3D Time.now
=3D> Mon Jan 16 21:27:58 CET 2006
irb(main):041:0> m =3D t.mon
=3D> 1
irb(main):042:0> nt =3D Time.mktime 2006, m + 1
=3D> Wed Feb 01 00:00:00 CET 2006
irb(main):043:0> p nt.strftime("%B")
"February"
=3D> nil
irb(main):044:0> nt =3D Time.mktime 2006, m + 2
=3D> Wed Mar 01 00:00:00 CET 2006
irb(main):045:0> p nt.strftime("%B")
"March"
=3D> nil


Cheers
detlef

Along with Time.mktime, there are Date methods to shift dates by a
number of months... Date#>> and Date#<< . Which you use depends on
whether you need Dates or Times.

irb(main):022:0> require 'date'
=3D> true
irb(main):023:0> bob =3D Date.today()
=3D> #<Date: 4907505/2,0,2299161>
irb(main):024:0> puts bob.strftime()
2006-01-17
=3D> nil
irb(main):025:0> puts bob.strftime("%B")
January
=3D> nil
irb(main):026:0> nextmonth =3D bob >> 1
=3D> #<Date: 4907567/2,0,2299161>
irb(main):027:0> puts nextmonth.strftime()
2006-02-17
=3D> nil
irb(main):028:0> puts nextmonth.strftime("%B")
February
=3D> nil
irb(main):029:0> one_after_that =3D bob >> 2
=3D> #<Date: 4907623/2,0,2299161>
irb(main):030:0> puts one_after_that.strftime()
2006-03-17
=3D> nil
irb(main):031:0> puts one_after_that.strftime("%B")
March
=3D> nil

-A

 

[Francis Hwang]

You might find this useful: http://rubyforge.org/projects/month/

 

[Adam Sanderson]

Just to compliment what was said above, you can do the following things
on a Date:
d = Date.today
d + 1 => Next Day
d - 1 => Previous Day
d >> 1 => Next Month
d << 1 => Previous Month

This is preferable to adding a known number of seconds to a time as is
done with Rails (time + 2.months) or in the posts above since months
can have a variable number of days, and your calculations will start to
get odd.

.adam

 

[David Brady]

irb(main):005:0> months[months.index(current), 42].size
=> 24

not good if the app is a mortage calculator! ;-)

Sorry if this response is too late to be useful to anyone, but here's a
solution that surprised me with its elegance. I read the OP and
immediately thought, "Oh, just spin forward 86,400 (seconds per day)
until the month changes" and, of course, someone had already posted this
reply. However, I wrote some code as a youth that played with dates
using division and moduli, and this post got me reminiscing on that.
Here's a resurrected version. I was very pleased to discover it handles
negative numbers, which made writing Time#prev_month trivial and elegant.

class Time
def next_month n=1
t = Time::mktime year + Integer(n)/12, ((month+n-1)%12)+1
t.strftime "%B"
end

def prev_month n=1
next_month -n
end
end

Cheers, and thanks for asking an interesting question!

-dB