This is probably an easy question but I am trying to get at the number
of days that are in a month. I have this calendar that I have built, the
idea being that when a month turns from February to March, for example,
the calendar should redisplay itself properly formated showing the new
month and the correct number of days. I have it so that it starts
counting the days on the right day of the week, but I have to know when
to stop counting. Any ideas, Thanks,

-S

On Thu, Feb 28, 2008 at 01:17:22AM +0900, Shandy Nantz wrote:
> This is probably an easy question but I am trying to get at the number
> of days that are in a month. I have this calendar that I have built, the
> idea being that when a month turns from February to March, for example,
> the calendar should redisplay itself properly formated showing the new
> month and the correct number of days. I have it so that it starts
> counting the days on the right day of the week, but I have to know when
> to stop counting. Any ideas, Thanks,

require 'date'

def days_in_month(month, year)
month = month.to_i
year = year.to_i
raise ArgumentError.new("invalid month") unless (1..12).to_a.include? month
first = Date.parse sprintf("%04d%02d01", year, month)
next_month = first + 32
(last - last.mday).mday
end

On 27/02/2008, Shandy Nantz <shandybleu> wrote:
>
> This is probably an easy question but I am trying to get at the number
> of days that are in a month. I have this calendar that I have built, the
> idea being that when a month turns from February to March, for example,
> the calendar should redisplay itself properly formated showing the new
> month and the correct number of days. I have it so that it starts
> counting the days on the right day of the week, but I have to know when
> to stop counting. Any ideas, Thanks,


i have not completely understood your problem, but there is a gem call
'date_utils' which does various calendar calculations.

See http://thopre.wordpress.com/2007/06/...e-week-200724/ for
some examples!

-Thomas

--=20
Thomas Preymesser
thopre
thomas
B=FCro: 030 - 830 353 88
mobil: 0176 - 75 03 03 04
Privat: 030 - 49 78 37 06
http://thopre.wordpress.com/
http://www.thopre.com/

On Feb 27, 2008, at 11:17 AM, Shandy Nantz wrote:

> This is probably an easy question but I am trying to get at the number
> of days that are in a month. I have this calendar that I have
> built, the
> idea being that when a month turns from February to March, for
> example,
> the calendar should redisplay itself properly formated showing the new
> month and the correct number of days. I have it so that it starts
> counting the days on the right day of the week, but I have to know
> when
> to stop counting. Any ideas, Thanks,

<code>
require "Date"
d = Date.new(2008, 2, -1)
d.day # => 29
</code>

You can find the last day of a month by creating a Date object for
day -1.

Regards, Morton

On Feb 27, 11:40 am, Gregory Seidman <gsslist+r>
wrote:
> On Thu, Feb 28, 2008 at 01:17:22AM +0900, Shandy Nantz wrote:
>
> require 'date'
>
> def days_in_month(month, year)
> month = month.to_i
> year = year.to_i
> raise ArgumentError.new("invalid month") unless (1..12).to_a.include? month
> first = Date.parse sprintf("%04d%02d01", year, month)
> next_month = first + 32
> (last - last.mday).mday
> end
>> --Greg

might want to try running that before posting

On Thu, Feb 28, 2008 at 02:49:54AM +0900, Brian Adkins wrote:
> On Feb 27, 11:40 am, Gregory Seidman <gsslist+r>
> wrote:
>
> might want to try running that before posting

Ah, details. Change the last line of the method to:

(next_month + next_month.mday).mday

Anyhow, it's worth noting that ActiveSupport includes Time.days_in_month.

--Greg

On Feb 27, 11:17 am, Shandy Nantz <shandyb> wrote:
> This is probably an easy question but I am trying to get at the number
> of days that are in a month. I have this calendar that I have built, the
> idea being that when a month turns from February to March, for example,
> the calendar should redisplay itself properly formated showing the new
> month and the correct number of days. I have it so that it starts
> counting the days on the right day of the week, but I have to know when
> to stop counting. Any ideas, Thanks,

require 'date'

def days_in_month year, month
((month < 12) ?
Date.new(year, month + 1) :
Date.new(year + 1, 1)).-(1).mday
end

puts days_in_month(2008,2) # => 29

On Feb 27, 12:07 pm, Morton Goldberg <m_goldb> wrote:
> On Feb 27, 2008, at 11:17 AM, Shandy Nantz wrote:
>> <code>
> require "Date"
> d = Date.new(2008, 2, -1)
> d.day # => 29
> </code>
>
> You can find the last day of a month by creating a Date object for
> day -1.
>
> Regards, Morton

And we have a winner :)

I wish I had read your post before posting mine. I need to read the
stdlib doc more carefully.

On Feb 27, 1:00 pm, Gregory Seidman <gsslist+r>
wrote:
> On Thu, Feb 28, 2008 at 02:49:54AM +0900, Brian Adkins wrote:
>>
>> Ah, details. Change the last line of the method to:
>
> (next_month + next_month.mday).mday
>
> Anyhow, it's worth noting that ActiveSupport includes Time.days_in_month.
>
> --Greg

You still didn't run it, did you? <sigh>

Some ideas you may want to consider:
1) it's probably reasonable to expect numeric month and day arguments,
so you can skip the .to_i calls
2) instead of creating a range, converting it to an array and calling
include?, wouldn't it be better to just use a simple comparison such
as "unless month > 0 && month < 13
3) sprintf'ing a date just to parse it is unnecessary & inefficient
4) it's still broken

On Thu, Feb 28, 2008 at 03:29:54AM +0900, Brian Adkins wrote:
> On Feb 27, 1:00 pm, Gregory Seidman <gsslist+r>
> wrote:
>
> You still didn't run it, did you? <sigh>

Don't sigh at me. I wrote some code off the cuff and fired it off. I also
didn't include unit tests. Yes, it was buggy and inefficient, but it got
across the approach I was using.

> Some ideas you may want to consider:
> 1) it's probably reasonable to expect numeric month and day arguments,
> so you can skip the .to_i calls

Given that it was for clarity, I think it's valuable.

> 2) instead of creating a range, converting it to an array and calling
> include?, wouldn't it be better to just use a simple comparison such
> as "unless month > 0 && month < 13

Arguable. I prefer range inclusion to a pair of comparisons, but that's a
matter of taste. The to_a only matters if I hadn't performed a to_i on the
month argument previously.

> 3) sprintf'ing a date just to parse it is unnecessary & inefficient

True enough. Date.new (a.k.a. Date.civil) takes year, month, and day
arguments. For that matter, as pointed out elsewhere in this thread, a -1
for the day argument gives the last day of the month, making the rest of
the method moot.

> 4) it's still broken

Typo. The + should have been a - in the correction. The correct, if
unnecessary, method is:

require 'date'

def days_in_month(month, year)
month = month.to_i
year = year.to_i
raise ArgumentError.new("invalid month") unless (1..12).include? month
first = Date.civil(year, month, 1)
next_month = first + 32
(next_month - next_month.mday).mday
end

An even simpler method, taken from elsewhere in the thread:

require 'date'

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

--Greg

Shandy Nantz wrote:
> This is probably an easy question but I am trying to get at the number
> of days that are in a month. I have this calendar that I have built, the
> idea being that when a month turns from February to March, for example,
> the calendar should redisplay itself properly formated showing the new
> month and the correct number of days. I have it so that it starts
> counting the days on the right day of the week, but I have to know when
> to stop counting. Any ideas, Thanks,
>
> -S
>
If you don't want to use the Date module, this is the plain old way:

def days_in_month(m=Time.new.month,y=Time.new.year)
return [31,0,31,30,31,30,31,31,30,31,30,31][m-1] unless m == 2
((y % 4 == 0) and ( (!(y % 100 == 0)) or (y % 400 == 0) ) ) ? 29 : 28
end

Dan

On Feb 27, 2008, at 2:17 PM, Gregory Seidman wrote:
> On Thu, Feb 28, 2008 at 03:29:54AM +0900, Brian Adkins wrote:

>
> Don't sigh at me. I wrote some code off the cuff and fired it off. I
> also
> didn't include unit tests. Yes, it was buggy and inefficient, but it
> got
> across the approach I was using.


The point is applicable to *everyone*:

"Don't present code that you haven't actually
run unless you *say* that you haven't run it."

You'll just end up confusing the OP or other readers that may benefit
from
the code. If you're trying to illustrate a point or an approach, say so
or make it quite clear that your code is incomplete or intended as
pseudo-code (particularly if it appears to be valid syntax).

-Rob

Rob Biedenharn http://agileconsultingllc.com
Rob

Gregory Seidman wrote:
> Don't sigh at me. I wrote some code off the cuff and fired it off. I
> also
> didn't include unit tests. Yes, it was buggy and inefficient, but it got
> across the approach I was using.
>

Thanks for caring, however this isn't a creative writing forum.

Rob Biedenharn wrote:

>
> The point is applicable to *everyone*:
>
> "Don't present code that you haven't actually
> run unless you *say* that you haven't run it."
>

Nah, better to let dubious code pop up now and then so that people are
not lulled into a false sense of security, and will hopefully realize
that, even if someone says they ran and tested the code and assure you
it's fine, the code may still be bad.

On Wed, Feb 27, 2008 at 2:14 PM, Rob Biedenharn
<Rob> wrote:
> The point is applicable to *everyone*:
>
> "Don't present code that you haven't actually
> run unless you *say* that you haven't run it."
>
> You'll just end up confusing the OP or other readers that may benefit
> from
> the code. If you're trying to illustrate a point or an approach, say so
> or make it quite clear that your code is incomplete or intended as
> pseudo-code (particularly if it appears to be valid syntax).
>
> -Rob

I frequently write bad code when I use a system where I cannot cut and
paste. All code on a forum, IMHO, should be taken with a grain of
salt. I don't think posted code needs to be perfect.

2c,
Todd