1 = Formats for Dates and Times
3 Several Ruby time-related classes have instance method +strftime+,
4 which returns a formatted string representing all or part of a date or time:
10 Each of these methods takes optional argument +format+,
11 which has zero or more embedded _format_ _specifications_ (see below).
13 Each of these methods returns the string resulting from replacing each
14 format specification embedded in +format+ with a string form
15 of one or more parts of the date or time.
19 Time.now.strftime('%H:%M:%S') # => "14:02:07"
21 A format specification has the form:
23 %[flags][width]conversion
27 - A leading percent character.
28 - Zero or more _flags_ (each is a character).
29 - An optional _width_ _specifier_ (an integer).
30 - A _conversion_ _specifier_ (a character).
32 Except for the leading percent character,
33 the only required part is the conversion specifier, so we begin with that.
35 == Conversion Specifiers
37 === \Date (Year, Month, Day)
39 - <tt>%Y</tt> - Year including century, zero-padded:
41 Time.now.strftime('%Y') # => "2022"
42 Time.new(-1000).strftime('%Y') # => "-1000" # Before common era.
43 Time.new(10000).strftime('%Y') # => "10000" # Far future.
44 Time.new(10).strftime('%Y') # => "0010" # Zero-padded by default.
46 - <tt>%y</tt> - Year without century, in range (0.99), zero-padded:
48 Time.now.strftime('%y') # => "22"
49 Time.new(1).strftime('%y') # => "01" # Zero-padded by default.
51 - <tt>%C</tt> - Century, zero-padded:
53 Time.now.strftime('%C') # => "20"
54 Time.new(-1000).strftime('%C') # => "-10" # Before common era.
55 Time.new(10000).strftime('%C') # => "100" # Far future.
56 Time.new(100).strftime('%C') # => "01" # Zero-padded by default.
58 - <tt>%m</tt> - Month of the year, in range (1..12), zero-padded:
60 Time.new(2022, 1).strftime('%m') # => "01" # Zero-padded by default.
61 Time.new(2022, 12).strftime('%m') # => "12"
63 - <tt>%B</tt> - Full month name, capitalized:
65 Time.new(2022, 1).strftime('%B') # => "January"
66 Time.new(2022, 12).strftime('%B') # => "December"
68 - <tt>%b</tt> - Abbreviated month name, capitalized:
70 Time.new(2022, 1).strftime('%b') # => "Jan"
71 Time.new(2022, 12).strftime('%h') # => "Dec"
73 - <tt>%h</tt> - Same as <tt>%b</tt>.
75 - <tt>%d</tt> - Day of the month, in range (1..31), zero-padded:
77 Time.new(2002, 1, 1).strftime('%d') # => "01"
78 Time.new(2002, 1, 31).strftime('%d') # => "31"
80 - <tt>%e</tt> - Day of the month, in range (1..31), blank-padded:
82 Time.new(2002, 1, 1).strftime('%e') # => " 1"
83 Time.new(2002, 1, 31).strftime('%e') # => "31"
85 - <tt>%j</tt> - Day of the year, in range (1..366), zero-padded:
87 Time.new(2002, 1, 1).strftime('%j') # => "001"
88 Time.new(2002, 12, 31).strftime('%j') # => "365"
90 === \Time (Hour, Minute, Second, Subsecond)
92 - <tt>%H</tt> - Hour of the day, in range (0..23), zero-padded:
94 Time.new(2022, 1, 1, 1).strftime('%H') # => "01"
95 Time.new(2022, 1, 1, 13).strftime('%H') # => "13"
97 - <tt>%k</tt> - Hour of the day, in range (0..23), blank-padded:
99 Time.new(2022, 1, 1, 1).strftime('%k') # => " 1"
100 Time.new(2022, 1, 1, 13).strftime('%k') # => "13"
102 - <tt>%I</tt> - Hour of the day, in range (1..12), zero-padded:
104 Time.new(2022, 1, 1, 1).strftime('%I') # => "01"
105 Time.new(2022, 1, 1, 13).strftime('%I') # => "01"
107 - <tt>%l</tt> - Hour of the day, in range (1..12), blank-padded:
109 Time.new(2022, 1, 1, 1).strftime('%l') # => " 1"
110 Time.new(2022, 1, 1, 13).strftime('%l') # => " 1"
112 - <tt>%P</tt> - Meridian indicator, lowercase:
114 Time.new(2022, 1, 1, 1).strftime('%P') # => "am"
115 Time.new(2022, 1, 1, 13).strftime('%P') # => "pm"
117 - <tt>%p</tt> - Meridian indicator, uppercase:
119 Time.new(2022, 1, 1, 1).strftime('%p') # => "AM"
120 Time.new(2022, 1, 1, 13).strftime('%p') # => "PM"
122 - <tt>%M</tt> - Minute of the hour, in range (0..59), zero-padded:
124 Time.new(2022, 1, 1, 1, 0, 0).strftime('%M') # => "00"
126 - <tt>%S</tt> - Second of the minute in range (0..59), zero-padded:
128 Time.new(2022, 1, 1, 1, 0, 0, 0).strftime('%S') # => "00"
130 - <tt>%L</tt> - Millisecond of the second, in range (0..999), zero-padded:
132 Time.new(2022, 1, 1, 1, 0, 0, 0).strftime('%L') # => "000"
134 - <tt>%N</tt> - Fractional seconds, default width is 9 digits (nanoseconds):
136 t = Time.now # => 2022-06-29 07:10:20.3230914 -0500
137 t.strftime('%N') # => "323091400" # Default.
139 Use {width specifiers}[rdoc-ref:strftime_formatting.rdoc@Width+Specifiers]
142 t.strftime('%3N') # => "323" # Milliseconds.
143 t.strftime('%6N') # => "323091" # Microseconds.
144 t.strftime('%9N') # => "323091400" # Nanoseconds.
145 t.strftime('%12N') # => "323091400000" # Picoseconds.
146 t.strftime('%15N') # => "323091400000000" # Femptoseconds.
147 t.strftime('%18N') # => "323091400000000000" # Attoseconds.
148 t.strftime('%21N') # => "323091400000000000000" # Zeptoseconds.
149 t.strftime('%24N') # => "323091400000000000000000" # Yoctoseconds.
151 - <tt>%s</tt> - Number of seconds since the epoch:
153 Time.now.strftime('%s') # => "1656505136"
157 - <tt>%z</tt> - Timezone as hour and minute offset from UTC:
159 Time.now.strftime('%z') # => "-0500"
161 - <tt>%Z</tt> - Timezone name (platform-dependent):
163 Time.now.strftime('%Z') # => "Central Daylight Time"
167 - <tt>%A</tt> - Full weekday name:
169 Time.now.strftime('%A') # => "Wednesday"
171 - <tt>%a</tt> - Abbreviated weekday name:
173 Time.now.strftime('%a') # => "Wed"
175 - <tt>%u</tt> - Day of the week, in range (1..7), Monday is 1:
177 t = Time.new(2022, 6, 26) # => 2022-06-26 00:00:00 -0500
178 t.strftime('%a') # => "Sun"
179 t.strftime('%u') # => "7"
181 - <tt>%w</tt> - Day of the week, in range (0..6), Sunday is 0:
183 t = Time.new(2022, 6, 26) # => 2022-06-26 00:00:00 -0500
184 t.strftime('%a') # => "Sun"
185 t.strftime('%w') # => "0"
189 - <tt>%U</tt> - Week number of the year, in range (0..53), zero-padded,
190 where each week begins on a Sunday:
192 t = Time.new(2022, 6, 26) # => 2022-06-26 00:00:00 -0500
193 t.strftime('%a') # => "Sun"
194 t.strftime('%U') # => "26"
196 - <tt>%W</tt> - Week number of the year, in range (0..53), zero-padded,
197 where each week begins on a Monday:
199 t = Time.new(2022, 6, 26) # => 2022-06-26 00:00:00 -0500
200 t.strftime('%a') # => "Sun"
201 t.strftime('%W') # => "25"
205 See {ISO 8601 week dates}[https://en.wikipedia.org/wiki/ISO_8601#Week_dates].
207 t0 = Time.new(2023, 1, 1) # => 2023-01-01 00:00:00 -0600
208 t1 = Time.new(2024, 1, 1) # => 2024-01-01 00:00:00 -0600
210 - <tt>%G</tt> - Week-based year:
212 t0.strftime('%G') # => "2022"
213 t1.strftime('%G') # => "2024"
215 - <tt>%g</tt> - Week-based year without century, in range (0..99), zero-padded:
217 t0.strftime('%g') # => "22"
218 t1.strftime('%g') # => "24"
220 - <tt>%V</tt> - Week number of the week-based year, in range (1..53),
223 t0.strftime('%V') # => "52"
224 t1.strftime('%V') # => "01"
228 - <tt>%n</tt> - Newline character "\n":
230 Time.now.strftime('%n') # => "\n"
232 - <tt>%t</tt> - Tab character "\t":
234 Time.now.strftime('%t') # => "\t"
236 - <tt>%%</tt> - Percent character '%':
238 Time.now.strftime('%%') # => "%"
240 === Shorthand Conversion Specifiers
242 Each shorthand specifier here is shown with its corresponding
245 - <tt>%c</tt> - \Date and time:
247 Time.now.strftime('%c') # => "Wed Jun 29 08:01:41 2022"
248 Time.now.strftime('%a %b %e %T %Y') # => "Wed Jun 29 08:02:07 2022"
250 - <tt>%D</tt> - \Date:
252 Time.now.strftime('%D') # => "06/29/22"
253 Time.now.strftime('%m/%d/%y') # => "06/29/22"
255 - <tt>%F</tt> - ISO 8601 date:
257 Time.now.strftime('%F') # => "2022-06-29"
258 Time.now.strftime('%Y-%m-%d') # => "2022-06-29"
260 - <tt>%v</tt> - VMS date:
262 Time.now.strftime('%v') # => "29-JUN-2022"
263 Time.now.strftime('%e-%^b-%4Y') # => "29-JUN-2022"
265 - <tt>%x</tt> - Same as <tt>%D</tt>.
267 - <tt>%X</tt> - Same as <tt>%T</tt>.
269 - <tt>%r</tt> - 12-hour time:
271 Time.new(2022, 1, 1, 1).strftime('%r') # => "01:00:00 AM"
272 Time.new(2022, 1, 1, 1).strftime('%I:%M:%S %p') # => "01:00:00 AM"
273 Time.new(2022, 1, 1, 13).strftime('%r') # => "01:00:00 PM"
274 Time.new(2022, 1, 1, 13).strftime('%I:%M:%S %p') # => "01:00:00 PM"
276 - <tt>%R</tt> - 24-hour time:
278 Time.new(2022, 1, 1, 1).strftime('%R') # => "01:00"
279 Time.new(2022, 1, 1, 1).strftime('%H:%M') # => "01:00"
280 Time.new(2022, 1, 1, 13).strftime('%R') # => "13:00"
281 Time.new(2022, 1, 1, 13).strftime('%H:%M') # => "13:00"
283 - <tt>%T</tt> - 24-hour time:
285 Time.new(2022, 1, 1, 1).strftime('%T') # => "01:00:00"
286 Time.new(2022, 1, 1, 1).strftime('%H:%M:%S') # => "01:00:00"
287 Time.new(2022, 1, 1, 13).strftime('%T') # => "13:00:00"
288 Time.new(2022, 1, 1, 13).strftime('%H:%M:%S') # => "13:00:00"
290 - <tt>%+</tt> (not supported in Time#strftime) - \Date and time:
292 DateTime.now.strftime('%+')
293 # => "Wed Jun 29 08:31:53 -05:00 2022"
294 DateTime.now.strftime('%a %b %e %H:%M:%S %Z %Y')
295 # => "Wed Jun 29 08:32:18 -05:00 2022"
299 Flags may affect certain formatting specifications.
301 Multiple flags may be given with a single conversion specified;
302 order does not matter.
306 - <tt>0</tt> - Pad with zeroes:
308 Time.new(10).strftime('%0Y') # => "0010"
310 - <tt>_</tt> - Pad with blanks:
312 Time.new(10).strftime('%_Y') # => " 10"
314 - <tt>-</tt> - Don't pad:
316 Time.new(10).strftime('%-Y') # => "10"
320 - <tt>^</tt> - Upcase result:
322 Time.new(2022, 1).strftime('%B') # => "January" # No casing flag.
323 Time.new(2022, 1).strftime('%^B') # => "JANUARY"
325 - <tt>#</tt> - Swapcase result:
327 Time.now.strftime('%p') # => "AM"
328 Time.now.strftime('%^p') # => "AM"
329 Time.now.strftime('%#p') # => "am"
333 - <tt>:</tt> - Put timezone as colon-separated hours and minutes:
335 Time.now.strftime('%:z') # => "-05:00"
337 - <tt>::</tt> - Put timezone as colon-separated hours, minutes, and seconds:
339 Time.now.strftime('%::z') # => "-05:00:00"
343 The integer width specifier gives a minimum width for the returned string:
345 Time.new(2002).strftime('%Y') # => "2002" # No width specifier.
346 Time.new(2002).strftime('%10Y') # => "0000002002"
347 Time.new(2002, 12).strftime('%B') # => "December" # No width specifier.
348 Time.new(2002, 12).strftime('%10B') # => " December"
349 Time.new(2002, 12).strftime('%3B') # => "December" # Ignored if too small.
351 = Specialized Format Strings
353 Here are a few specialized format strings,
354 each based on an external standard.
358 The HTTP date format is based on
359 {RFC 2616}[https://www.rfc-editor.org/rfc/rfc2616],
360 and treats dates in the format <tt>'%a, %d %b %Y %T GMT'</tt>:
362 d = Date.new(2001, 2, 3) # => #<Date: 2001-02-03>
363 # Return HTTP-formatted string.
364 httpdate = d.httpdate # => "Sat, 03 Feb 2001 00:00:00 GMT"
365 # Return new date parsed from HTTP-formatted string.
366 Date.httpdate(httpdate) # => #<Date: 2001-02-03>
367 # Return hash parsed from HTTP-formatted string.
368 Date._httpdate(httpdate)
369 # => {:wday=>6, :mday=>3, :mon=>2, :year=>2001, :hour=>0, :min=>0, :sec=>0, :zone=>"GMT", :offset=>0}
373 The RFC 3339 date format is based on
374 {RFC 3339}[https://www.rfc-editor.org/rfc/rfc3339]:
376 d = Date.new(2001, 2, 3) # => #<Date: 2001-02-03>
377 # Return 3339-formatted string.
378 rfc3339 = d.rfc3339 # => "2001-02-03T00:00:00+00:00"
379 # Return new date parsed from 3339-formatted string.
380 Date.rfc3339(rfc3339) # => #<Date: 2001-02-03>
381 # Return hash parsed from 3339-formatted string.
382 Date._rfc3339(rfc3339)
383 # => {:year=>2001, :mon=>2, :mday=>3, :hour=>0, :min=>0, :sec=>0, :zone=>"+00:00", :offset=>0}
387 The RFC 2822 date format is based on
388 {RFC 2822}[https://www.rfc-editor.org/rfc/rfc2822],
389 and treats dates in the format <tt>'%a, %-d %b %Y %T %z'</tt>]:
391 d = Date.new(2001, 2, 3) # => #<Date: 2001-02-03>
392 # Return 2822-formatted string.
393 rfc2822 = d.rfc2822 # => "Sat, 3 Feb 2001 00:00:00 +0000"
394 # Return new date parsed from 2822-formatted string.
395 Date.rfc2822(rfc2822) # => #<Date: 2001-02-03>
396 # Return hash parsed from 2822-formatted string.
397 Date._rfc2822(rfc2822)
398 # => {:wday=>6, :mday=>3, :mon=>2, :year=>2001, :hour=>0, :min=>0, :sec=>0, :zone=>"+0000", :offset=>0}
402 The JIS X 0301 format includes the
403 {Japanese era name}[https://en.wikipedia.org/wiki/Japanese_era_name],
404 and treats dates in the format <tt>'%Y-%m-%d'</tt>
405 with the first letter of the romanized era name prefixed:
407 d = Date.new(2001, 2, 3) # => #<Date: 2001-02-03>
408 # Return 0301-formatted string.
409 jisx0301 = d.jisx0301 # => "H13.02.03"
410 # Return new date parsed from 0301-formatted string.
411 Date.jisx0301(jisx0301) # => #<Date: 2001-02-03>
412 # Return hash parsed from 0301-formatted string.
413 Date._jisx0301(jisx0301) # => {:year=>2001, :mon=>2, :mday=>3}
415 == ISO 8601 Format Specifications
417 This section shows format specifications that are compatible with
418 {ISO 8601}[https://en.wikipedia.org/wiki/ISO_8601].
419 Details for various formats may be seen at the links.
421 Examples in this section assume:
423 t = Time.now # => 2022-06-29 16:49:25.465246 -0500
427 See {ISO 8601 dates}[https://en.wikipedia.org/wiki/ISO_8601#Dates].
429 - {Years}[https://en.wikipedia.org/wiki/ISO_8601#Years]:
431 - Basic year (+YYYY+):
433 t.strftime('%Y') # => "2022"
435 - Expanded year (<tt>±YYYYY</tt>):
437 t.strftime('+%5Y') # => "+02022"
438 t.strftime('-%5Y') # => "-02022"
440 - {Calendar dates}[https://en.wikipedia.org/wiki/ISO_8601#Calendar_dates]:
442 - Basic date (+YYYYMMDD+):
444 t.strftime('%Y%m%d') # => "20220629"
446 - Extended date (<tt>YYYY-MM-DD</tt>):
448 t.strftime('%Y-%m-%d') # => "2022-06-29"
450 - Reduced extended date (<tt>YYYY-MM</tt>):
452 t.strftime('%Y-%m') # => "2022-06"
454 - {Week dates}[https://en.wikipedia.org/wiki/ISO_8601#Week_dates]:
456 - Basic date (+YYYYWww+ or +YYYYWwwD+):
458 t.strftime('%Y%Ww') # => "202226w"
459 t.strftime('%Y%Ww%u') # => "202226w3"
461 - Extended date (<tt>YYYY-Www</tt> or <tt>YYYY-Www-D<tt>):
463 t.strftime('%Y-%Ww') # => "2022-26w"
464 t.strftime('%Y-%Ww-%u') # => "2022-26w-3"
466 - {Ordinal dates}[https://en.wikipedia.org/wiki/ISO_8601#Ordinal_dates]:
468 - Basic date (+YYYYDDD+):
470 t.strftime('%Y%j') # => "2022180"
472 - Extended date (<tt>YYYY-DDD</tt>):
474 t.strftime('%Y-%j') # => "2022-180"
478 See {ISO 8601 times}[https://en.wikipedia.org/wiki/ISO_8601#Times].
482 - Basic time (+Thhmmss.sss+, +Thhmmss+, +Thhmm+, or +Thh+):
484 t.strftime('T%H%M%S.%L') # => "T164925.465"
485 t.strftime('T%H%M%S') # => "T164925"
486 t.strftime('T%H%M') # => "T1649"
487 t.strftime('T%H') # => "T16"
489 - Extended time (+Thh:mm:ss.sss+, +Thh:mm:ss+, or +Thh:mm+):
491 t.strftime('T%H:%M:%S.%L') # => "T16:49:25.465"
492 t.strftime('T%H:%M:%S') # => "T16:49:25"
493 t.strftime('T%H:%M') # => "T16:49"
495 - {Time zone designators}[https://en.wikipedia.org/wiki/ISO_8601#Time_zone_designators]:
497 - Timezone (+time+ represents a valid time,
498 +hh+ represents a valid 2-digit hour,
499 and +mm+ represents a valid 2-digit minute):
501 - Basic timezone (<tt>time±hhmm</tt>, <tt>time±hh</tt>, or +timeZ+):
503 t.strftime('T%H%M%S%z') # => "T164925-0500"
504 t.strftime('T%H%M%S%z').slice(0..-3) # => "T164925-05"
505 t.strftime('T%H%M%SZ') # => "T164925Z"
507 - Extended timezone (<tt>time±hh:mm</tt>):
509 t.strftime('T%H:%M:%S%z') # => "T16:49:25-0500"
513 - {Local time (unqualified)}[https://en.wikipedia.org/wiki/ISO_8601#Local_time_(unqualified)].
514 - {Coordinated Universal Time (UTC)}[https://en.wikipedia.org/wiki/ISO_8601#Coordinated_Universal_Time_(UTC)].
515 - {Time offsets from UTC}[https://en.wikipedia.org/wiki/ISO_8601#Time_offsets_from_UTC].
517 === Combined \Date and \Time
519 See {ISO 8601 Combined date and time representations}[https://en.wikipedia.org/wiki/ISO_8601#Combined_date_and_time_representations].
521 An ISO 8601 combined date and time representation may be any
522 ISO 8601 date and any ISO 8601 time,
523 separated by the letter +T+.
525 For the relevant +strftime+ formats, see
526 {Dates}[rdoc-ref:strftime_formatting.rdoc@Dates]
527 and {Times}[rdoc-ref:strftime_formatting.rdoc@Times] above.