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1. Introduction to %form-date.r
This library script is for inclusion in other programs and allows sophisticated date formatting, ala strftime, but not exactly
2. form-date At a Glance
>> form-date now "%A %e%i %B, %Y at %T" == "Thursday 26th April, 2007 at 00:44:12" >> form-date now "%d-%b-%Y/%H:%M:%S%Z" == "26-Apr-2007/00:49:39-04:00" >> now == 26-Apr-2007/0:52:13-4:00 >> form-date now/precise "%c" == "19-Jul-2007/00:01:45.108242-04:00"
3. Using %form-date.r
Including this function is simple. Just DO it.
>> do %form-date.r
or to execute this right out of the rebol.org library
>> do http://www.rebol.org/download-a-script.r?script-name=form-date.rYou now have the form-date function
>> help form-date
USAGE:
FORM-DATE date format /gmt
DESCRIPTION:
Renders a date to a given format (largely compatible with strftime)
FORM-DATE is a function value.
ARGUMENTS:
date -- (Type: date)
format -- (Type: any-string)
REFINEMENTS:
/gmt -- Align time with GMT
4. The format string
Ordinary characters placed in the format string are inserted into return value without conversion. Conversion specifications are introduced by a % character, and terminated by a conversion specifier character, and are replaced and inserted into return value as follows:
| %a | The abbreviated weekday name according to the current locale. |
| %A | The full weekday name according to the current locale. |
| %b | The abbreviated month name according to the current locale. |
| %B | The full month name according to the current locale. |
| %c | The preferred date and time representation for the current locale. In this case the locale is REBOLand, with a little %b mixed in. |
| %C | The century number (year/100) as a 2-digit integer. |
| %d | The day of the month as a decimal number (range 01 to 31). |
| %D | Equivalent to %Y/%m/%d. |
| %e | Like %d, the day of the month as a decimal number, without a leading zero. |
| %G | The ISO 8601 year with century as a decimal number. The 4-digit year corresponding to the ISO week number (see %V). This has the same format and value as %y, except that if the ISO week number belongs to the previous or next year, that year is used instead. |
| %g | Like %G, but without century, i.e., with a 2-digit year (00-99). |
| %H | The hour as a decimal number using a 24-hour clock (range 00 to 23). |
| %i | The english suffix for numeric value, st for 01, th for 04. |
| %I | The hour as a decimal number using a 12-hour clock (range 01 to 12). |
| %j | The day of the year as a decimal number (range 001 to 366). |
| %J | Like %j, but without leading zeroes. |
| %m | The month as a decimal number (range 01 to 12). |
| %M | The minute as a decimal number (range 00 to 59). |
| %p | Either "AM" or "PM" according to the given time value. Noon is treated as "PM" and midnight as "AM". |
| %s | The second as a decimal number 00-60 with REBOL nanosecond precision, a period followed by 6 digits. |
| %S | The second as a decimal number (range 00 to 60). (The range is up to 60 to allow for occasional leap seconds.) |
| %t | A tab character. |
| %T | The time in 24-hour notation (%H:%M:%S). |
| %u | The day of the week as a decimal, range 1 to 7, Monday being 1. See also %w. |
| %U | The week number of the current year as a decimal number, range 00 to 53, starting with the first Sunday as the first day of week 01. See also %V and %W. |
| %V | The ISO 8601:1988 week number of the current year as a decimal number, range 01 to 53, where week 1 is the first week that has at least 4 days in the current year, and with Monday as the first day of the week. See also %U and %W. |
| %w | The day of the week as a decimal, range 0 to 6, Sunday being 0. See also %u. |
| %W | The week number of the current year as a decimal number, range 00 to 53, starting with the first Monday as the first day of week 01. |
| %y | The year as a decimal number without a century (range 00 to 99). |
| %Y | The year as a decimal number including the century. |
| %Z | The time-zone as hour offset from GMT. |
| %% | A literal "%" character. |
5. What you can learn
The interpolate function, along with date-codes is an excellent example of parse. The dialect created is the two character format specifiers that produce the date and time pieces. A strftime dialect.
REBOL can emulate the functionality of other systems, while still remaining REBOL.
REBOL code can look world-class elegant when properly formatted and factored.
6. What you can break
The date! parameter has to be a date!. If you use any time related format specifiers, it has to be a date! that includes time information or returned fields may be incorrect.
>> form-date now/date "%T" == "00:00:00" >> form-date now/time "%T" Script Error: form-date expected date argument of type: date Near: form-date now/time "%T" >> form-date now "%T" == "02:29:39"
7. What's new
With the addition of %c, you have clean, always the same length REBOL time-stamps.
>> 01-Jan-0001/00:00:00.000000-00:00 == 1-Jan-0001/0:00 >> form-date 01-Jan-0001/00:00:00.000000-00:00 "%c" == "01-Jan-0001/00:00:00.000000+00:00" >> form-date now/precise "%c" == "19-Jul-2007/00:42:53.586560-04:00" >> form-date now "%c" == "19-Jul-2007/00:43:19.000000-04:00"
7.1. Precision versus Accuracy
Please note that now/precise while reporting 6 digit precision for the sub-seconds, is only as accurate as your computer clock will allow.
8. Credits
- %form-date.r original author: Christopher Ross-Gill
- Part of QuarterMaster, %qm.r by Christopher Ross-Gill http://www.ross-gill.com/
- Usage document by Brian Tiffin, Library Team Apprentice, Last updated: 19-Feb-2009