time conversion function ?

I have a variable time in the number of days such as 1 to 366 and I was
wondering if there is a simple function that will convert it to the month
and day of the month. I can do it myself, but I was just wondering if there
is an easy builtin function that I could use. I am using Visual C++.
Normally, I use strftime as it is very useful and has many options, but I
did not see a way to convert the days of the year to month and day.

Z.K.

Tom
Thu Jun 21 09:51:35 CDT 2007

I don't know of a "built in" way to do this sort of calculation. As you
say, it would be easy enough to figure it out in a small function. You
could figure out the month by creating a cumulative array of month/days and
the day would be whatever is left over. You'd have to account for leap year
so that would mean you'd need to know the current year. That is pretty easy
to get :o)

http://www.codeproject.com/cpp/LeapYear.asp

Tom

"Z.K." <nospam@nospam.net> wrote in message
news:eghRpHBtHHA.1168@TK2MSFTNGP02.phx.gbl...
>I have a variable time in the number of days such as 1 to 366 and I was
>wondering if there is a simple function that will convert it to the month
>and day of the month. I can do it myself, but I was just wondering if
>there is an easy builtin function that I could use. I am using Visual C++.
>Normally, I use strftime as it is very useful and has many options, but I
>did not see a way to convert the days of the year to month and day.
>
> Z.K.
>

Victor
Thu Jun 21 09:57:23 CDT 2007

Z.K. wrote:
> I have a variable time in the number of days such as 1 to 366 and I
> was wondering if there is a simple function that will convert it to
> the month and day of the month. I can do it myself, but I was just
> wondering if there is an easy builtin function that I could use. I
> am using Visual C++. Normally, I use strftime as it is very useful
> and has many options, but I did not see a way to convert the days of
> the year to month and day.

There is no standard function to do that. Roll your own.

V
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I do not respond to top-posted replies, please don't ask

Bill
Thu Jun 21 10:03:46 CDT 2007

Not relevant :-) but it is such a lovely algorithm (sort of):

static int dayofweek( int year, int month, int day)
{
#if 0
Zeller's Congruence
Where: weekday = (0=Sun, 1=Mon, 2=Tue, 3=Wed, 4=Thu, 5=Fri, 6=Sat)

day = day of the month

month = month of year (Jan & Feb = 13 & 14 of prev year)

year = year (year - 1 if month is Jan or Feb)

INT = integer part (eg: INT(3.5) = 3)

MOD = modulus or remainder part (eg: (10 MOD 7) = 3)


Example: Feb 12, 1809 day = 12, month = 14, year = 1808 (weekday = 0 Sun)

Jul 4, 1776 day = 4, month = 7, year = 1776 (weekday = 4 Thu)
#endif

if ( month==1 || month==2 )
month += 12, year -= 1;

return ( ( day + 1
+ ( month * 2 )
+ (int)( ( month + 1 ) * 3 / 5 )
+ year
+ (int)( year / 4 )
- (int)( year / 100 )
+ ( year / 400 ) ) % 7 );
}


"Tom Serface" <tom.nospam@camaswood.com> wrote in message
news:%237bOHPBtHHA.1168@TK2MSFTNGP02.phx.gbl...
>I don't know of a "built in" way to do this sort of calculation. As you
>say, it would be easy enough to figure it out in a small function. You
>could figure out the month by creating a cumulative array of month/days and
>the day would be whatever is left over. You'd have to account for leap
>year so that would mean you'd need to know the current year. That is
>pretty easy to get :o)
>
> http://www.codeproject.com/cpp/LeapYear.asp
>
> Tom
>
> "Z.K." <nospam@nospam.net> wrote in message
> news:eghRpHBtHHA.1168@TK2MSFTNGP02.phx.gbl...
>>I have a variable time in the number of days such as 1 to 366 and I was
>>wondering if there is a simple function that will convert it to the month
>>and day of the month. I can do it myself, but I was just wondering if
>>there is an easy builtin function that I could use. I am using Visual
>>C++. Normally, I use strftime as it is very useful and has many options,
>>but I did not see a way to convert the days of the year to month and day.
>>
>> Z.K.
>>
>

Z
Thu Jun 21 11:23:44 CDT 2007

Ok, thanks, that is about what I expected.

Z.K.

"Tom Serface" <tom.nospam@camaswood.com> wrote in message
news:%237bOHPBtHHA.1168@TK2MSFTNGP02.phx.gbl...
>I don't know of a "built in" way to do this sort of calculation. As you
>say, it would be easy enough to figure it out in a small function. You
>could figure out the month by creating a cumulative array of month/days and
>the day would be whatever is left over. You'd have to account for leap
>year so that would mean you'd need to know the current year. That is
>pretty easy to get :o)
>
> http://www.codeproject.com/cpp/LeapYear.asp
>
> Tom
>
> "Z.K." <nospam@nospam.net> wrote in message
> news:eghRpHBtHHA.1168@TK2MSFTNGP02.phx.gbl...
>>I have a variable time in the number of days such as 1 to 366 and I was
>>wondering if there is a simple function that will convert it to the month
>>and day of the month. I can do it myself, but I was just wondering if
>>there is an easy builtin function that I could use. I am using Visual
>>C++. Normally, I use strftime as it is very useful and has many options,
>>but I did not see a way to convert the days of the year to month and day.
>>
>> Z.K.
>>
>

Ben
Thu Jun 21 12:22:23 CDT 2007


"Z.K." <nospam@nospam.net> wrote in message
news:eghRpHBtHHA.1168@TK2MSFTNGP02.phx.gbl...
>I have a variable time in the number of days such as 1 to 366 and I was
>wondering if there is a simple function that will convert it to the month
>and day of the month. I can do it myself, but I was just wondering if
>there is an easy builtin function that I could use. I am using Visual C++.
>Normally, I use strftime as it is very useful and has many options, but I
>did not see a way to convert the days of the year to month and day.
>

Fill in a tm structure with Jan 1 of the year.
Use mktime to convert to time_t
time_t is measured in seconds, so you can adjust it yourself (add 60 * 60 *
24 * days)
Use gmtime to get back to a tm structure with month and day