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getFirstDayOfMonth()

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  getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-01 03:48 +0000
    Re: getFirstDayOfMonth() gazelle@shell.xmission.com (Kenny McCormack) - 2024-03-01 15:39 +0000
      Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-01 17:12 +0100
        Re: getFirstDayOfMonth() Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-01 08:28 -0800
          Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-01 17:33 +0100
            Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-01 17:37 +0100
              Re: getFirstDayOfMonth() Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-01 10:34 -0800
                Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-01 22:03 +0100
          Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-01 17:20 +0000
      Re: getFirstDayOfMonth() scott@slp53.sl.home (Scott Lurndal) - 2024-03-01 16:47 +0000
      Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-01 17:56 +0100
      Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-01 17:18 +0000
      Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-01 20:47 +0000
        Re: getFirstDayOfMonth() scott@slp53.sl.home (Scott Lurndal) - 2024-03-01 21:38 +0000
          Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-01 21:50 +0000
            Re: getFirstDayOfMonth() Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-03 09:52 -0800
          Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-02 00:00 +0000
            Re: getFirstDayOfMonth() scott@slp53.sl.home (Scott Lurndal) - 2024-03-02 14:46 +0000
              Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-02 16:41 +0100
              Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-02 19:59 +0000
                Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-02 22:14 +0100
                  Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-04 18:08 +0000
                    Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-05 03:03 +0100
                Re: getFirstDayOfMonth() Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-02 14:22 -0800
                  Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-03 15:43 +0100
                    Re: getFirstDayOfMonth() David Brown <david.brown@hesbynett.no> - 2024-03-03 18:45 +0100
                      Re: getFirstDayOfMonth() Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-03 18:42 +0000
                        Re: getFirstDayOfMonth() David Brown <david.brown@hesbynett.no> - 2024-03-04 09:49 +0100
                      Re: getFirstDayOfMonth() Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2024-03-04 11:31 +0000
                        Re: getFirstDayOfMonth() Richard Harnden <richard.nospam@gmail.invalid> - 2024-03-04 14:23 +0000
                      Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-04 17:27 +0100
                    Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-04 17:34 +0000
                      Re: getFirstDayOfMonth() scott@slp53.sl.home (Scott Lurndal) - 2024-03-04 17:40 +0000
                        Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-04 18:11 +0000
                          Re: getFirstDayOfMonth() scott@slp53.sl.home (Scott Lurndal) - 2024-03-04 18:26 +0000
                            Re: getFirstDayOfMonth() Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-04 18:30 +0000
                              Re: getFirstDayOfMonth() scott@slp53.sl.home (Scott Lurndal) - 2024-03-04 19:01 +0000
                            Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-05 03:09 +0100
                              Re: getFirstDayOfMonth() scott@slp53.sl.home (Scott Lurndal) - 2024-03-05 15:06 +0000
                      Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-05 02:56 +0100
                        Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-05 02:49 +0000
                        Re: getFirstDayOfMonth() Mark Bourne <nntp.mbourne@spamgourmet.com> - 2024-03-06 20:40 +0000
                          Re: getFirstDayOfMonth() scott@slp53.sl.home (Scott Lurndal) - 2024-03-06 20:54 +0000
                  Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-04 17:26 +0000
                    Re: getFirstDayOfMonth() scott@slp53.sl.home (Scott Lurndal) - 2024-03-04 17:34 +0000
                      Re: getFirstDayOfMonth() Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-04 10:07 -0800
                      Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-04 23:47 +0000
                        Re: getFirstDayOfMonth() Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-04 16:10 -0800
                        Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-05 00:12 +0000
                          [OT] Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-05 03:18 +0100
                            Re: [OT] Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-05 02:55 +0000
                        Re: getFirstDayOfMonth() scott@slp53.sl.home (Scott Lurndal) - 2024-03-05 15:03 +0000
                          Re: getFirstDayOfMonth() Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-05 13:25 -0800
                    Re: getFirstDayOfMonth() Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2024-03-04 21:21 +0000
                      Re: getFirstDayOfMonth() Michael S <already5chosen@yahoo.com> - 2024-03-05 00:37 +0200
                        Re: getFirstDayOfMonth() Michael S <already5chosen@yahoo.com> - 2024-03-05 11:41 +0200
                        Re: getFirstDayOfMonth() Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-14 15:57 -0700
                      Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-04 23:35 +0000
                      Re: getFirstDayOfMonth() Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-03-05 03:20 +0100
                Re: getFirstDayOfMonth() James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-03-03 04:06 -0500
                  Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-04 18:21 +0000
                    Re: getFirstDayOfMonth() James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-03-04 14:42 -0500
                    Re: getFirstDayOfMonth() Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-04 14:50 -0800
                      Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-05 00:40 +0000
                        Re: getFirstDayOfMonth() Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-05 01:27 +0000
                          Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-05 02:40 +0000
                          Re: getFirstDayOfMonth() scott@slp53.sl.home (Scott Lurndal) - 2024-03-05 15:05 +0000
                        Re: getFirstDayOfMonth() Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-04 17:39 -0800
                          Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-05 02:43 +0000
                    Re: getFirstDayOfMonth() Michael S <already5chosen@yahoo.com> - 2024-03-05 01:08 +0200
                      Re: getFirstDayOfMonth() porkchop@invalid.foo (Mike Sanders) - 2024-03-05 00:18 +0000
                        Re: getFirstDayOfMonth() Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-04 16:33 -0800
                Re: getFirstDayOfMonth() scott@slp53.sl.home (Scott Lurndal) - 2024-03-03 15:24 +0000
                  Re: getFirstDayOfMonth() Michael S <already5chosen@yahoo.com> - 2024-03-03 20:20 +0200
                    Re: getFirstDayOfMonth() scott@slp53.sl.home (Scott Lurndal) - 2024-03-03 18:56 +0000
              Re: getFirstDayOfMonth() Mark Bourne <nntp.mbourne@spamgourmet.com> - 2024-03-03 13:17 +0000
      Re: getFirstDayOfMonth() jak <nospam@please.ty> - 2024-03-02 02:49 +0100
        Re: getFirstDayOfMonth() Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-03 09:47 -0800
          Re: getFirstDayOfMonth() jak <nospam@please.ty> - 2024-03-04 02:26 +0100
        Re: getFirstDayOfMonth() Peter 'Shaggy' Haywood <phaywood@alphalink.com.au> - 2024-03-05 14:03 +1100
          Re: getFirstDayOfMonth() bart <bc@freeuk.com> - 2024-03-05 13:19 +0000
            Re: getFirstDayOfMonth() jak <nospam@please.ty> - 2024-03-13 05:40 +0100
              Re: getFirstDayOfMonth() jak <nospam@please.ty> - 2024-03-13 06:01 +0100
                Re: getFirstDayOfMonth() Spiros Bousbouras <spibou@gmail.com> - 2024-03-13 13:38 +0000
                  Re: getFirstDayOfMonth() Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-13 08:47 -0700
                    Re: getFirstDayOfMonth() Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-13 09:11 -0700
                Re: getFirstDayOfMonth() Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-03-13 07:36 -0700
                  Re: getFirstDayOfMonth() Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-03-14 19:56 -0700
      Re: getFirstDayOfMonth() Kaz Kylheku <433-929-6894@kylheku.com> - 2024-03-02 03:44 +0000
        Re: getFirstDayOfMonth() Peter 'Shaggy' Haywood <phaywood@alphalink.com.au> - 2024-03-05 14:07 +1100
        Re: getFirstDayOfMonth() gazelle@shell.xmission.com (Kenny McCormack) - 2024-03-05 13:30 +0000

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#383208 — getFirstDayOfMonth()

Just sharing what I've learned, hope some of you can adapt
it for your own use.

Calculates the name of the weekday (Sun, Mon, etc) for the
1st day of a given month & year...

https://busybox.neocities.org/notes/get-first-day-of-month.txt

-- 
:wq
Mike Sanders

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#383214

In article <urrj5l$124o9$1@dont-email.me>,
Mike Sanders <porkchop@invalid.foo> wrote:
>Just sharing what I've learned, hope some of you can adapt
>it for your own use.
>
>Calculates the name of the weekday (Sun, Mon, etc) for the
>1st day of a given month & year...
>
>https://busybox.neocities.org/notes/get-first-day-of-month.txt

Here's the guts of my version of the Zeller algorithm:

int day(d,m,y)
int d, m, y;
{
    if (m < 3) {
        m += 12;
        y--;
    }
        return (d + (13*m-27)/5 + y + y/4 - y/100 + y/400) % 7;
}

I assume the two versions end up being equivalent.

BTW, how long do you think it will be until this thread gets hijacked into
a long, acrimonious debate about what the definition of the first day of
the month is and how various cultures define it differently, and how
insensitive we are (especially, if "we" are USA Americans) to assume that
our way is the only way?  A matter of hours, I suspect.

-- 
You know politics has really been turned upside down when you have someone in the
government with a last name of Cheney (Liz, Senator from Wyoming) who is the voice of
reason.

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#383215

On 01.03.2024 16:39, Kenny McCormack wrote:
> In article <urrj5l$124o9$1@dont-email.me>,
> Mike Sanders <porkchop@invalid.foo> wrote:
>> Just sharing what I've learned, hope some of you can adapt
>> it for your own use.
>>
>> Calculates the name of the weekday (Sun, Mon, etc) for the
>> 1st day of a given month & year...
>>
>> https://busybox.neocities.org/notes/get-first-day-of-month.txt
> 
> Here's the guts of my version of the Zeller algorithm:
> 
> int day(d,m,y)
> int d, m, y;
> {
>     if (m < 3) {
>         m += 12;
>         y--;
>     }
>         return (d + (13*m-27)/5 + y + y/4 - y/100 + y/400) % 7;
> }
> 
> I assume the two versions end up being equivalent.

Are they?

I'm certainly irritated about the OP's final

  return (f % 7) - 1;

returning values from -1 to 5. And then using these indexes
to address a C array. (Looks wrong to me, but I'm anyway
not interested in second hand copies of generally available
algorithms; there's little value.)

Janis

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#383216

Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
[...]
>> In article <urrj5l$124o9$1@dont-email.me>,
>> Mike Sanders <porkchop@invalid.foo> wrote:
>>> Just sharing what I've learned, hope some of you can adapt
>>> it for your own use.
>>>
>>> Calculates the name of the weekday (Sun, Mon, etc) for the
>>> 1st day of a given month & year...
>>>
>>> https://busybox.neocities.org/notes/get-first-day-of-month.txt
[...]
> I'm certainly irritated about the OP's final
>
>   return (f % 7) - 1;
>
> returning values from -1 to 5. And then using these indexes
> to address a C array. (Looks wrong to me, but I'm anyway
> not interested in second hand copies of generally available
> algorithms; there's little value.)

Yes, that's a bug in the original code.  The program only tests for
August 2024, but the algorithm fails for June 2024, which starts on
Saturday.

One fix is to change
    return (f % 7) - 1;
to:
    return (f + 6) % 7;
which works correctly at least for all months of 2024.

Negative index values can be valid.  For example, foo[-1] can be valid,
but only if foo is a pointer to an array element other than the first
one, not if foo is an array object.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Medtronic
void Void(void) { Void(); } /* The recursive call of the void */

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#383217

On 01.03.2024 17:28, Keith Thompson wrote:
> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
> [...]
>>> In article <urrj5l$124o9$1@dont-email.me>,
>>> Mike Sanders <porkchop@invalid.foo> wrote:
>>>> Just sharing what I've learned, hope some of you can adapt
>>>> it for your own use.
>>>>
>>>> Calculates the name of the weekday (Sun, Mon, etc) for the
>>>> 1st day of a given month & year...
>>>>
>>>> https://busybox.neocities.org/notes/get-first-day-of-month.txt
> [...]
>> I'm certainly irritated about the OP's final
>>
>>   return (f % 7) - 1;
>>
>> returning values from -1 to 5. And then using these indexes
>> to address a C array. (Looks wrong to me, but I'm anyway
>> not interested in second hand copies of generally available
>> algorithms; there's little value.)
> 
> Yes, that's a bug in the original code.  The program only tests for
> August 2024, but the algorithm fails for June 2024, which starts on
> Saturday.
> 
> One fix is to change
>     return (f % 7) - 1;
> to:
>     return (f + 6) % 7;
> which works correctly at least for all months of 2024.

Yes. Though I'd have done the correction on the previous line.

   int f = d + ... - 1;
   return  f % 7;

To me that would be clearer.

Janis

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#383218

On 01.03.2024 17:33, Janis Papanagnou wrote:
> 
> Yes. Though I'd have done the correction on the previous line.
> 
>    int f = d + ... - 1;
>    return  f % 7;
> 
> To me that would be clearer.

Or completely removing the 'd' and the '-1' since 'd' is actually
a (non-const declared) constant and equals to 1.

(Gee! Why do I mind, anyway.)

> 
> Janis
> 

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#383226

Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
> On 01.03.2024 17:33, Janis Papanagnou wrote:
>> Yes. Though I'd have done the correction on the previous line.
>> 
>>    int f = d + ... - 1;
>>    return  f % 7;
>> 
>> To me that would be clearer.
>
> Or completely removing the 'd' and the '-1' since 'd' is actually
> a (non-const declared) constant and equals to 1.
>
> (Gee! Why do I mind, anyway.)

I think the point of defining 'd' is to allow for computing the day of
the week for days of the month other than the first.  The code as
presented suggests a lot of opportunities for generalization (such as
handling months other than August 2024).  The local variable 'd' could
be replaced by a parameter 'int mday'.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Medtronic
void Void(void) { Void(); } /* The recursive call of the void */

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#383230

On 01.03.2024 19:34, Keith Thompson wrote:
> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
>> On 01.03.2024 17:33, Janis Papanagnou wrote:
>>> Yes. Though I'd have done the correction on the previous line.
>>>
>>>    int f = d + ... - 1;
>>>    return  f % 7;
>>>
>>> To me that would be clearer.
>>
>> Or completely removing the 'd' and the '-1' since 'd' is actually
>> a (non-const declared) constant and equals to 1.
>>
>> (Gee! Why do I mind, anyway.)
> 
> I think the point of defining 'd' is to allow for computing the day of
> the week for days of the month other than the first.  The code as
> presented suggests a lot of opportunities for generalization (such as
> handling months other than August 2024).  The local variable 'd' could
> be replaced by a parameter 'int mday'.

Surely I am aware of that. But the OP's code isn't addressing any
generalization (cf. "int getFirstDayOfMonth(int year, int month)").
If you'd strive for a generalization you'd define a function like
the one Kenny posted (cf. "int day(d,m,y)"). If you want a special
function (for whatever reason) as the OP did you can as well just
optimize it by reducing redundant parts. (Anyway, it's not worth
the dispute.)

Janis

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#383224

Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:

> Yes, that's a bug in the original code.  The program only tests for
> August 2024, but the algorithm fails for June 2024, which starts on
> Saturday.
> 
> One fix is to change
>     return (f % 7) - 1;
> to:
>     return (f + 6) % 7;
> which works correctly at least for all months of 2024.
> 
> Negative index values can be valid.  For example, foo[-1] can be valid,
> but only if foo is a pointer to an array element other than the first
> one, not if foo is an array object.

Thanks Keith, will use this moving forward. Glad to have some extra
eyeballs on it.

-- 
:wq
Mike Sanders

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#383219

gazelle@shell.xmission.com (Kenny McCormack) writes:
>In article <urrj5l$124o9$1@dont-email.me>,
>Mike Sanders <porkchop@invalid.foo> wrote:
>>Just sharing what I've learned, hope some of you can adapt
>>it for your own use.
>>
>>Calculates the name of the weekday (Sun, Mon, etc) for the
>>1st day of a given month & year...
>>
>>https://busybox.neocities.org/notes/get-first-day-of-month.txt
>
>Here's the guts of my version of the Zeller algorithm:
>
>int day(d,m,y)
>int d, m, y;
>{
>    if (m < 3) {
>        m += 12;
>        y--;
>    }
>        return (d + (13*m-27)/5 + y + y/4 - y/100 + y/400) % 7;
>}
>
>I assume the two versions end up being equivalent.
>
>BTW, how long do you think it will be until this thread gets hijacked into
>a long, acrimonious debate about what the definition of the first day of
>the month is and how various cultures define it differently, and how
>insensitive we are (especially, if "we" are USA Americans) to assume that
>our way is the only way?  A matter of hours, I suspect.

Seconds, it would appear, as you have highjacked your own thread.

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#383221

On 01.03.2024 16:39, Kenny McCormack wrote:
> 
> Here's the guts of my version of the Zeller algorithm:
> 
> int day(d,m,y)
> int d, m, y;
> {
>     if (m < 3) {
>         m += 12;
>         y--;
>     }
>         return (d + (13*m-27)/5 + y + y/4 - y/100 + y/400) % 7;
> }

I'm wondering what would be the better approach, using some date
functions or calculating it by a formula. (Serious question.)

I'm asking since I had previously used time-functions in another
context (determining Fri 13th dates) for such a purpose. And the
rewrite to the "first day" task is simple, and the code pattern
very flexible. Here's the Gawk counterpart just for illustration:

  BEGIN { y = ARGV[1] ; m = ARGV[2]
    print strftime ("%a", mktime (y " " m " 1 0 0 0"))
  }

...and I'm sure you can also use this approach in C.

So what's more advantageous? - Is the domain of one or the other
approach restricted? Is one or the other more accurate? Or may
the runtime be an issue?

Janis

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#383223

Kenny McCormack <gazelle@shell.xmission.com> wrote:

> Here's the guts of my version of the Zeller algorithm:
> 
> int day(d,m,y)
> int d, m, y;
> {
>     if (m < 3) {
>         m += 12;
>         y--;
>     }
>         return (d + (13*m-27)/5 + y + y/4 - y/100 + y/400) % 7;
> }
> 
> I assume the two versions end up being equivalent.

Hey-hey Kenny!

Many thanks for sharing this, now I have something to compare it too
more thoroughly.
 
> BTW, how long do you think it will be until this thread gets hijacked into
> a long, acrimonious debate about what the definition of the first day of
> the month is and how various cultures define it differently, and how
> insensitive we are (especially, if "we" are USA Americans) to assume that
> our way is the only way?  A matter of hours, I suspect.

Well...

-- 
:wq
Mike Sanders

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#383228

Kenny McCormack <gazelle@shell.xmission.com> wrote:

> Here's the guts of my version of the Zeller algorithm:
> 
> int day(d,m,y)
> int d, m, y;
> {
>     if (m < 3) {
>         m += 12;
>         y--;
>     }
>         return (d + (13*m-27)/5 + y + y/4 - y/100 + y/400) % 7;
> }

I've put this right to work too Kenny...

Prints calander for the given year with every 2 months adjacent

https://busybox.neocities.org/notes/adjacent-calendars.txt

Example...

 Jan                            Feb
 Sun Mon Tue Wed Thu Fri Sat    Sun Mon Tue Wed Thu Fri Sat
                           1              1   2   3   4   5
   2   3   4   5   6   7   8      6   7   8   9  10  11  12
   9  10  11  12  13  14  15     13  14  15  16  17  18  19
  16  17  18  19  20  21  22     20  21  22  23  24  25  26
  23  24  25  26  27  28  29     27  28
  30  31

-- 
:wq
Mike Sanders

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#383232

porkchop@invalid.foo (Mike Sanders) writes:
>Kenny McCormack <gazelle@shell.xmission.com> wrote:
>
>> Here's the guts of my version of the Zeller algorithm:
>> 
>> int day(d,m,y)
>> int d, m, y;
>> {
>>     if (m < 3) {
>>         m += 12;
>>         y--;
>>     }
>>         return (d + (13*m-27)/5 + y + y/4 - y/100 + y/400) % 7;
>> }
>
>I've put this right to work too Kenny...
>
>Prints calander for the given year with every 2 months adjacent
>
>https://busybox.neocities.org/notes/adjacent-calendars.txt
>
>Example...
>
> Jan                            Feb
> Sun Mon Tue Wed Thu Fri Sat    Sun Mon Tue Wed Thu Fri Sat
>                           1              1   2   3   4   5
>   2   3   4   5   6   7   8      6   7   8   9  10  11  12
>   9  10  11  12  13  14  15     13  14  15  16  17  18  19
>  16  17  18  19  20  21  22     20  21  22  23  24  25  26
>  23  24  25  26  27  28  29     27  28
>  30  31

That must not have been for 2024, or you have a bug.

A calendar utility comes with most linux systems. It also supports
ISO 8601 which starts the week on Monday instead of Sunday.

https://en.wikipedia.org/wiki/ISO_8601

https://github.com/util-linux/util-linux/blob/master/misc-utils/cal.c

$ cal 2024
                               2024                               

       January               February                 March       
Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa
    1  2  3  4  5  6                1  2  3                   1  2   
 7  8  9 10 11 12 13    4  5  6  7  8  9 10    3  4  5  6  7  8  9   
14 15 16 17 18 19 20   11 12 13 14 15 16 17   10 11 12 13 14 15 16   
21 22 23 24 25 26 27   18 19 20 21 22 23 24   17 18 19 20 21 22 23   
28 29 30 31            25 26 27 28 29         24 25 26 27 28 29 30   
                                              31                   

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#383233

Scott Lurndal <scott@slp53.sl.home> wrote:

> That must not have been for 2024, or you have a bug.

Well Scott, in the code of the link posted its displaying 2022:

int year = 2022;
 
> A calendar utility comes with most linux systems. It also supports
> ISO 8601 which starts the week on Monday instead of Sunday.

Yes sir, I know that. But I want to build my own instead so I can
learn more about it. Even if that means reiventing the wheel, at
least I'll learn it as I wish. Hoping not to sound contrite,
cant we all just help each other learn? Darn man.

-- 
:wq
Mike Sanders

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#383265

porkchop@invalid.foo (Mike Sanders) writes:

> Scott Lurndal <scott@slp53.sl.home> wrote:
>
>> That must not have been for 2024, or you have a bug.
>
> Well Scott, in the code of the link posted its displaying 2022:
>
> int year = 2022;
>
>> A calendar utility comes with most linux systems.  It also supports
>> ISO 8601 which starts the week on Monday instead of Sunday.
>
> Yes sir, I know that.  But I want to build my own instead so I can
> learn more about it.  Even if that means reiventing the wheel, at
> least I'll learn it as I wish.  Hoping not to sound contrite,
> cant we all just help each other learn?  Darn man.

If you want to reinvent wheels, I suggest looking for some
rather more interesting wheels.

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#383235

Scott Lurndal <scott@slp53.sl.home> wrote:

> https://en.wikipedia.org/wiki/ISO_8601

Have partial ISO8601 compliance now (when using option: -D=2):

Usage: DATES [-OPTIONS] FILE1 [FILE2 ...]

-A=NUM  Number of days in advance to look ahead (366 max)
-P=NUM  Number of days in the past to look back (366 max)
-D=NUM  Format dates as: 1 mm/dd/yyyy, 2 yyyy/mm/dd
-S=NUM  Separate date fields using: 1 Slash, 2 Dash, 3 Dot
-X=NUM  Export results as: 1 TXT, 2 CSV, 3 SQL, 4 HTML
-T=TAG  Filter results for 'TAG' (16 characters max)
-H      Include holidays (see manual for list)
-W      Include weekday abbreviations
-F      Include attribute flags (see manual for details)
-C      Display calendar for current year
-M      Display embedded user manual

Error levels returned:

3  Option syntax errors
2  File open-read errors
1  Dates match today or matching tags
0  No dates match today or no tags match

But hey its Friday I should lighten up & have some fun:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

const char *getChineseZodiac(int year) {

    const char* animals[] = {
        "Rat", "Ox", "Tiger", "Rabbit", "Dragon", "Snake",
        "Horse", "Goat", "Monkey", "Rooster", "Dog", "Pig"
    };

    return animals[year % 12];
}

int main() {

    time_t now = time(NULL);
    struct tm *localTime = localtime(&now);
    int year = localTime->tm_year;
    printf("%d Year of the %s\n", year + 1900, getChineseZodiac(year));

    return 0;
}

-- 
:wq
Mike Sanders

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#383242

porkchop@invalid.foo (Mike Sanders) writes:
>Scott Lurndal <scott@slp53.sl.home> wrote:
>
>> https://en.wikipedia.org/wiki/ISO_8601
>
>Have partial ISO8601 compliance now (when using option: -D=2):

Nice.

>
>Usage: DATES [-OPTIONS] FILE1 [FILE2 ...]
>
>-A=NUM  Number of days in advance to look ahead (366 max)
>-P=NUM  Number of days in the past to look back (366 max)
>-D=NUM  Format dates as: 1 mm/dd/yyyy, 2 yyyy/mm/dd
>-S=NUM  Separate date fields using: 1 Slash, 2 Dash, 3 Dot
>-X=NUM  Export results as: 1 TXT, 2 CSV, 3 SQL, 4 HTML
>-T=TAG  Filter results for 'TAG' (16 characters max)
>-H      Include holidays (see manual for list)
>-W      Include weekday abbreviations
>-F      Include attribute flags (see manual for details)
>-C      Display calendar for current year
>-M      Display embedded user manual
>

If I may suggest:

https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html

'-h'  or '-?' have traditionally been used to display
usage information for an utility.

>Error levels returned:
>
>3  Option syntax errors
>2  File open-read errors
>1  Dates match today or matching tags
>0  No dates match today or no tags match

For commands defined by POSIX (and generally in
unix), an exit status of zero indicates success.

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#383243

On 02.03.2024 15:46, Scott Lurndal wrote:
> porkchop@invalid.foo (Mike Sanders) writes:
>>
>> Usage: DATES [-OPTIONS] FILE1 [FILE2 ...]
>>[...]
> 
> If I may suggest:
> 
> https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html
> 
> '-h'  or '-?' have traditionally been used to display
> usage information for an utility.

Or, since there's a mandatory file name argument, provide usage
information (also) if no argument or option is provided.

Janis

> [...]

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#383244

Scott Lurndal <scott@slp53.sl.home> wrote:

> If I may suggest:
> 
> https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html
> 
> '-h'  or '-?' have traditionally been used to display
> usage information for an utility.

Yep, it will definitely be '-?' (still working to finalize things).

Many thanks for the link too btw.
 
>>Error levels returned:
>>
>>3  Option syntax errors
>>2  File open-read errors
>>1  Dates match today or matching tags
>>0  No dates match today or no tags match
> 
> For commands defined by POSIX (and generally in
> unix), an exit status of zero indicates success.

Oh yeah. Have been wrestling with the potential
consequences of this for a good while. I think I'm
going leave it as is because, (only speaking for
myself here) the POSIX 0 good, 1 bad is terrible.
This is perhaps the only area I've ever seen where
other OSs, like Windows, have a superior methodology
on the issue. 0/1 provides next to no nuance. But
I'm no expert, just my experience.

Thanks again for the links Scott, I'll read them this
weekend.

-- 
:wq
Mike Sanders

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