# Days in a year

How do I get number of days in a year?

PÃ¥l BergstrÃ¶m wrote:

How do I get number of days in a year?

Enter “number of days in a year” into Google and you’ll get some useful
results.

The very first hit gives you
http://en.wikipedia.org/wiki/Leap_year#Algorithm

Just check if the year is leap. In google u’ll find something like:

int __isleap <javascript:searchRef(’__isleap’)>(int
year<javascript:searchRef(‘year’)>)
{
/* every fourth year is a leap year except for century years that are

• not divisible by 400. /
/
return (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0)); */
return (!(year <javascript:searchRef(‘year’)>%4) &&
((year<javascript:searchRef(‘year’)>%100)
|| !(year <javascript:searchRef(‘year’)>%400)));
}

On Mon, Oct 27, 2008 at 9:12 AM, Pål Bergström [email protected] wrote:

How do I get number of days in a year?

You can use the date library…

require ‘date’; puts Date.new(2005) - Date.new(2004)
=> 366

Todd

Todd B. wrote:

On Mon, Oct 27, 2008 at 9:12 AM, Pï¿½l Bergstrï¿½m [email protected] wrote:

How do I get number of days in a year?

You can use the date library…

require ‘date’; puts Date.new(2005) - Date.new(2004)
=> 366

Todd

So there’s nothing like this (Rails)

Time.days_in_month()

A stupid question in the first place. I’ve done like this; I check if
Feb in a particular year has 29 days or not, so it gives 365 or 366
days. Simple.

On Mon, Oct 27, 2008 at 1:20 PM, PÃ¥l BergstrÃ¶m [email protected]
wrote:

So there’s nothing like this (Rails)

Time.days_in_month()

You could just “require ‘activesupport’”

or look at the code in activesupport…

class Time
COMMON_YEAR_DAYS_IN_MONTH = [nil, 31, 28, 31, 30, 31, 30, 31, 31,
30, 31, 30, 31]
class << self
# Return the number of days in the given month.
# If no year is specified, it will use the current year.
def days_in_month(month, year = now.year)
return 29 if month == 2 && ::Date.gregorian_leap?(year)
COMMON_YEAR_DAYS_IN_MONTH[month]
end
end
end

PÃ¥l BergstrÃ¶m wrote:

A stupid question in the first place. I’ve done like this; I check if
Feb in a particular year has 29 days or not, so it gives 365 or 366
days. Simple.

And notice how days_in_month is implemented in activesupport:

``````      def days_in_month(month, year = now.year)
return 29 if month == 2 && ::Date.gregorian_leap?(year)
COMMON_YEAR_DAYS_IN_MONTH[month]
end
``````

So all you need is:

irb(main):001:0> require ‘date’
=> true
irb(main):002:0> Date.gregorian_leap?(2008) ? 366 : 365
=> 366
irb(main):003:0> Date.gregorian_leap?(2009) ? 366 : 365
=> 365

Brian C. [email protected] wrote:

So all you need is:

irb(main):001:0> require ‘date’
=> true
irb(main):002:0> Date.gregorian_leap?(2008) ? 366 : 365 => 366
irb(main):003:0> Date.gregorian_leap?(2009) ? 366 : 365 => 365

Or ask the day of year of December 31st:

require ‘date’

DateTime.new(2008, 12, 31).yday # => 366

DateTime.new(2009, 12, 31).yday # => 365

Best regards,
Jan F.

Jan F. wrote:

Brian C. [email protected] wrote:

Or ask the day of year of December 31st:

require ‘date’

DateTime.new(2008, 12, 31).yday # => 366

DateTime.new(2009, 12, 31).yday # => 365

Best regards,
Jan F.

That was smart. Thanks!

Brian C. [email protected] wrote:

So all you need is:

irb(main):001:0> require ‘date’
=> true
irb(main):002:0> Date.gregorian_leap?(2008) ? 366 : 365 => 366
irb(main):003:0> Date.gregorian_leap?(2009) ? 366 : 365 => 365

Or ask the day of year of December 31st:

require ‘date’
DateTime.new(2008, 12, 31).yday # => 366
DateTime.new(2009, 12, 31).yday # => 366

Best regards,
Jan F.

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