Asp Forum - How do I add x months to a date

Ben Edwards

7/3/2007 2:14:00 PM

I have a date

my_date = Date.new( 2007, 1, 1 )

I then have a variable holding an integer

months_to_add = 4

How do i add 'months_to_add' to my_date'?

I have spent ages googeling and looking in o'reilly ruby cookbook but no luck;(

Any ideas?

Ben
--
Ben Edwards - Bristol, UK
If you have a problem emailing me use
http://www.gurtlush.org.uk/profiles...
(email address this email is sent from may be defunct)

9 Answers

Tim Hunter

7/3/2007 2:36:00 PM

On Jul 3, 10:13 am, "Ben Edwards" <funkyt...@gmail.com> wrote:
> I have a date
>
> my_date = Date.new( 2007, 1, 1 )
>
> I then have a variable holding an integer
>
> months_to_add = 4
>
> How do i add 'months_to_add' to my_date'?
>
> I have spent ages googeling and looking in o'reilly ruby cookbook but no luck;(
>
> Any ideas?

My first question is "which 4 months?" Adding January, February,
March, and April is different from adding June, July, and August and
September.

However, let's assume that you know which four and can determine the
number of days in your 4 months. According to ri, Date defines the "+"
method, so it should be as simple as

my_new_date = my_date + days_to_add

Daniel Lucraft

7/3/2007 3:19:00 PM

Ben Edwards wrote:
> I have a date
>
> my_date = Date.new( 2007, 1, 1 )
>
> I then have a variable holding an integer
>
> months_to_add = 4
>
> How do i add 'months_to_add' to my_date'?
>
> I have spent ages googeling and looking in o'reilly ruby cookbook but no
> luck;(
>
> Any ideas?
>
> Ben

I would do it like this, if I didn't mind loading some helpful
ActiveSupport junk:

irb> require 'active_support/core_ext/numeric'
=> true
irb> require 'active_support/core_ext/date'
=> true

irb> my_date = Date.new( 2007, 1, 1 )
=> #<Date: 4908203/2,0,2299161>

irb> my_time = my_date.to_time
=> Mon Jan 01 00:00:00 +0000 2007

irb> months_to_add = 4
=> 4

irb> new_time = my_time + months_to_add.months
=> Tue May 01 01:00:00 +0100 2007

irb> new_date = Date.new(new_time.year, new_time.month, new_time.day)
=> #<Date: 4908443/2,0,2299161>

best,
Dan

--
Posted via http://www.ruby-....

Ben Edwards

7/3/2007 3:22:00 PM

On 03/07/07, Glen Holcomb <damnbigman@gmail.com> wrote:
> And when I say string you could do better and use a hash or an array.
>
> On 7/3/07, Glen Holcomb <damnbigman@gmail.com> wrote:
> >
> > You can't do it directly, date objects are immutable.
> >
> > You could always get the date value from the object and then parse it, add
> > the number of months you want and then create a new date object. That
> > seems
> > like a bit of a waste though. I would keep the date value in a string and
> > manipulate it there, if and when I needed an actual date object with that
> > value I would create a date object and give that out.

This all seems like a lot of messing around for what should be a
standard operation. This type of thing must exist in one of the
standard libraries.

Ben

> > On 7/3/07, Ben Edwards <funkytwig@gmail.com> wrote:
> > >
> > > I have a date
> > >
> > > my_date = Date.new( 2007, 1, 1 )
> > >
> > > I then have a variable holding an integer
> > >
> > > months_to_add = 4
> > >
> > > How do i add 'months_to_add' to my_date'?
> > >
> > > I have spent ages googeling and looking in o'reilly ruby cookbook but no
> > > luck;(
> > >
> > > Any ideas?
> > >
> > > Ben
> > > --
> > > Ben Edwards - Bristol, UK
> > > If you have a problem emailing me use
> > > http://www.gurtlush.org.uk/profiles...
> > > (email address this email is sent from may be defunct)
> > >
> > >
> >
> >
> > --
> > "Hey brother christian with your high and mighty errand, Your actions
> > speak
> > so loud, I can't hear a word you're saying."
> >
> > -Greg Graffin (Bad Religion)
> >
>
>
>
> --
> "Hey brother christian with your high and mighty errand, Your actions speak
> so loud, I can't hear a word you're saying."
>
> -Greg Graffin (Bad Religion)
>

--
Ben Edwards - Bristol, UK
If you have a problem emailing me use
http://www.gurtlush.org.uk/profiles...
(email address this email is sent from may be defunct)

Daniel Lucraft

7/3/2007 3:36:00 PM

Ben Edwards wrote:
> On 03/07/07, Glen Holcomb <damnbigman@gmail.com> wrote:
>> > manipulate it there, if and when I needed an actual date object with that
>> > value I would create a date object and give that out.
>
> This all seems like a lot of messing around for what should be a
> standard operation. This type of thing must exist in one of the
> standard libraries.
>
> Ben

Actually, you are totally right. The '>>' operator does what is
required:

irb> my_date = Date.new( 2007, 1, 1 )
=> #<Date: 4908203/2,0,2299161>

irb> my_date.to_s
=> "2007-01-01"
irb> (my_date >> 4).to_s
=> "2007-05-01"

best,
Dan

--
Posted via http://www.ruby-....

Gavin Kistner

7/4/2007 2:29:00 AM

On Jul 3, 8:13 am, "Ben Edwards" <funkyt...@gmail.com> wrote:
> I have a date
>
> my_date = Date.new( 2007, 1, 1 )
>
> I then have a variable holding an integer
>
> months_to_add = 4
>
> How do i add 'months_to_add' to my_date'?

# http://phrogz.net/RubyLibs/rdoc/files/MutableTi...

irb(main):001:0> require 'MutableTime'
=> true

irb(main):002:0> my_date = MutableTime.new( 2007, 1, 1 )
=> Thu Feb 01 00:00:00 -0700 2007

irb(main):003:0> my_date.month += 4
=> 5

irb(main):004:0> my_date
=> Fri Jun 01 00:00:00 -0600 2007

Raimon Fs

12/7/2007 10:54:00 AM

Daniel Lucraft wrote:
> Ben Edwards wrote:
>> On 03/07/07, Glen Holcomb <damnbigman@gmail.com> wrote:
>>> > manipulate it there, if and when I needed an actual date object with that
>>> > value I would create a date object and give that out.
>>
>> This all seems like a lot of messing around for what should be a
>> standard operation. This type of thing must exist in one of the
>> standard libraries.
>>
>> Ben
>
> Actually, you are totally right. The '>>' operator does what is
> required:
>
> irb> my_date = Date.new( 2007, 1, 1 )
> => #<Date: 4908203/2,0,2299161>
>
> irb> my_date.to_s
> => "2007-01-01"
> irb> (my_date >> 4).to_s
> => "2007-05-01"
>
> best,
> Dan

I couldn't find any info about this operator >> with dates.

So, for example, if I have 2007-01-01 and I want to know the last day of
adding three months (2007-03-31) I would do:

d = Date.new(2007,1,1)
((d >> 3)-1).to_s

it works, but we can relay on this operations ?

regards,

rai

--
Posted via http://www.ruby-....

Lloyd Linklater

12/7/2007 12:34:00 PM

Ben Edwards wrote:
> I have a date
>
> my_date = Date.new( 2007, 1, 1 )
>
> I then have a variable holding an integer
>
> months_to_add = 4
>
> How do i add 'months_to_add' to my_date'?
>
> I have spent ages googeling and looking in o'reilly ruby cookbook but no
> luck;(
>
> Any ideas?
>
> Ben

I have not tried this but I know of something in rails that sounds
similar:
http://railshelp.com/ActiveSupport::CoreExtensions::Date::Calculations#...

What if you could do something like this:

my_date = Date.new( 2007, 1, 1 )
months_to_add = 4
my_date = my_date.months_ago(months_to_add * -1)

Negative of months_ago could do it.

Shot in the dark but GL!
--
Posted via http://www.ruby-....

Raimon Fs

12/7/2007 1:58:00 PM

Lloyd Linklater wrote:
> Ben Edwards wrote:
>> I have a date
>>
>> my_date = Date.new( 2007, 1, 1 )
>>
>> I then have a variable holding an integer
>>
>> months_to_add = 4
>>
>> How do i add 'months_to_add' to my_date'?
>>
>> I have spent ages googeling and looking in o'reilly ruby cookbook but no
>> luck;(
>>
>> Any ideas?
>>
>> Ben
>
> I have not tried this but I know of something in rails that sounds
> similar:
> http://railshelp.com/ActiveSupport::CoreExtensions::Date::Calculations#...

I wasn't aware of this, thanks !!!

I'm using Rails so I'll try to use it.

I prefer to do in Ruby if it's possible ...

> What if you could do something like this:
>
> my_date = Date.new( 2007, 1, 1 )
> months_to_add = 4
> my_date = my_date.months_ago(months_to_add * -1)
>
> Negative of months_ago could do it.
>
> Shot in the dark but GL!

I'll try it ...

thanks,

rai
--
Posted via http://www.ruby-....

Rick DeNatale

12/7/2007 4:45:00 PM

On 12/7/07, Raimon Fs <coder@montx.com> wrote:

> I couldn't find any info about this operator >> with dates.
>
> So, for example, if I have 2007-01-01 and I want to know the last day of
> adding three months (2007-03-31) I would do:
>
> d = Date.new(2007,1,1)
> ((d >> 3)-1).to_s
>
> it works, but we can relay on this operations ?

It's standard Ruby

shadowfax:~/ssanta rick$ qri "Date#<<"
---------------------------------------------------------------- Date#<<
<<(n)
------------------------------------------------------------------------
Return a new Date object that is n months earlier than the current
one.

If the day-of-the-month of the current Date is greater than the
last day of the target month, the day-of-the-month of the returned
Date will be the last day of the target month.

shadowfax:~/ssanta rick$ qri "Date#>>"
---------------------------------------------------------------- Date#>>
>>(n)
------------------------------------------------------------------------
Return a new Date object that is n months later than the current
one.

If the day-of-the-month of the current Date is greater than the
last day of the target month, the day-of-the-month of the returned
Date will be the last day of the target month.

--
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denh...

comp.lang.ruby

How do I add x months to a date

Ben Edwards

Tim Hunter

Daniel Lucraft

Ben Edwards

Daniel Lucraft

Gavin Kistner

Raimon Fs

Lloyd Linklater

Raimon Fs

Rick DeNatale

x Login to ForumsZone