strftime
strftime(p1)
public
Formats time according to the directives in the given format string. The directives begins with a percent (%) character. Any text not listed as a directive will be passed through to the output string.
The directive consists of a percent (%) character, zero or more flags, optional minimum field width, optional modifier and a conversion specifier as follows.
%<flags><width><modifier><conversion>
Flags:
- don't pad a numerical output. _ use spaces for padding. 0 use zeros for padding. ^ upcase the result string. # change case. : use colons for %z.
The minimum field width specifies the minimum width.
The modifier is “E” and “O”. They are ignored.
Format directives:
Date (Year, Month, Day): %Y - Year with century (can be negative, 4 digits at least) -0001, 0000, 1995, 2009, 14292, etc. %C - year / 100 (round down. 20 in 2009) %y - year % 100 (00..99) %m - Month of the year, zero-padded (01..12) %_m blank-padded ( 1..12) %-m no-padded (1..12) %B - The full month name (``January'') %^B uppercased (``JANUARY'') %b - The abbreviated month name (``Jan'') %^b uppercased (``JAN'') %h - Equivalent to %b %d - Day of the month, zero-padded (01..31) %-d no-padded (1..31) %e - Day of the month, blank-padded ( 1..31) %j - Day of the year (001..366) Time (Hour, Minute, Second, Subsecond): %H - Hour of the day, 24-hour clock, zero-padded (00..23) %k - Hour of the day, 24-hour clock, blank-padded ( 0..23) %I - Hour of the day, 12-hour clock, zero-padded (01..12) %l - Hour of the day, 12-hour clock, blank-padded ( 1..12) %P - Meridian indicator, lowercase (``am'' or ``pm'') %p - Meridian indicator, uppercase (``AM'' or ``PM'') %M - Minute of the hour (00..59) %S - Second of the minute (00..60) %L - Millisecond of the second (000..999) %N - Fractional seconds digits, default is 9 digits (nanosecond) %3N millisecond (3 digits) %6N microsecond (6 digits) %9N nanosecond (9 digits) %12N picosecond (12 digits) Time zone: %z - Time zone as hour and minute offset from UTC (e.g. +0900) %:z - hour and minute offset from UTC with a colon (e.g. +09:00) %::z - hour, minute and second offset from UTC (e.g. +09:00:00) %Z - Time zone abbreviation name Weekday: %A - The full weekday name (``Sunday'') %^A uppercased (``SUNDAY'') %a - The abbreviated name (``Sun'') %^a uppercased (``SUN'') %u - Day of the week (Monday is 1, 1..7) %w - Day of the week (Sunday is 0, 0..6) ISO 8601 week-based year and week number: The week 1 of YYYY starts with a Monday and includes YYYY-01-04. The days in the year before the first week are in the last week of the previous year. %G - The week-based year %g - The last 2 digits of the week-based year (00..99) %V - Week number of the week-based year (01..53) Week number: The week 1 of YYYY starts with a Sunday or Monday (according to %U or %W). The days in the year before the first week are in week 0. %U - Week number of the year. The week starts with Sunday. (00..53) %W - Week number of the year. The week starts with Monday. (00..53) Seconds since the Epoch: %s - Number of seconds since 1970-01-01 00:00:00 UTC. Literal string: %n - Newline character (\n) %t - Tab character (\t) %% - Literal ``%'' character Combination: %c - date and time (%a %b %e %T %Y) %D - Date (%m/%d/%y) %F - The ISO 8601 date format (%Y-%m-%d) %v - VMS date (%e-%^b-%4Y) %x - Same as %D %X - Same as %T %r - 12-hour time (%I:%M:%S %p) %R - 24-hour time (%H:%M) %T - 24-hour time (%H:%M:%S)
This method is similar to strftime() function defined in ISO C and POSIX. Several directives (%a, %A, %b, %B, %c, %p, %r, %x, %X, %E*, %O* and %Z) are locale dependent in the function. However this method is locale independent since Ruby 1.9. So, the result may differ even if a same format string is used in other systems such as C. It is good practice to avoid %x and %X because there are corresponding locale independent representations, %D and %T.
Examples:
t = Time.new(2007,11,19,8,37,48,"-06:00") #=> 2007-11-19 08:37:48 -0600 t.strftime("Printed on %m/%d/%Y") #=> "Printed on 11/19/2007" t.strftime("at %I:%M%p") #=> "at 08:37AM"
Various ISO 8601 formats:
%Y%m%d => 20071119 Calendar date (basic) %F => 2007-11-19 Calendar date (extended) %Y-%m => 2007-11 Calendar date, reduced accuracy, specific month %Y => 2007 Calendar date, reduced accuracy, specific year %C => 20 Calendar date, reduced accuracy, specific century %Y%j => 2007323 Ordinal date (basic) %Y-%j => 2007-323 Ordinal date (extended) %GW%V%u => 2007W471 Week date (basic) %G-W%V-%u => 2007-W47-1 Week date (extended) %GW%V => 2007W47 Week date, reduced accuracy, specific week (basic) %G-W%V => 2007-W47 Week date, reduced accuracy, specific week (extended) %H%M%S => 083748 Local time (basic) %T => 08:37:48 Local time (extended) %H%M => 0837 Local time, reduced accuracy, specific minute (basic) %H:%M => 08:37 Local time, reduced accuracy, specific minute (extended) %H => 08 Local time, reduced accuracy, specific hour %H%M%S,%L => 083748,000 Local time with decimal fraction, comma as decimal sign (basic) %T,%L => 08:37:48,000 Local time with decimal fraction, comma as decimal sign (extended) %H%M%S.%L => 083748.000 Local time with decimal fraction, full stop as decimal sign (basic) %T.%L => 08:37:48.000 Local time with decimal fraction, full stop as decimal sign (extended) %H%M%S%z => 083748-0600 Local time and the difference from UTC (basic) %T%:z => 08:37:48-06:00 Local time and the difference from UTC (extended) %Y%m%dT%H%M%S%z => 20071119T083748-0600 Date and time of day for calendar date (basic) %FT%T%:z => 2007-11-19T08:37:48-06:00 Date and time of day for calendar date (extended) %Y%jT%H%M%S%z => 2007323T083748-0600 Date and time of day for ordinal date (basic) %Y-%jT%T%:z => 2007-323T08:37:48-06:00 Date and time of day for ordinal date (extended) %GW%V%uT%H%M%S%z => 2007W471T083748-0600 Date and time of day for week date (basic) %G-W%V-%uT%T%:z => 2007-W47-1T08:37:48-06:00 Date and time of day for week date (extended) %Y%m%dT%H%M => 20071119T0837 Calendar date and local time (basic) %FT%R => 2007-11-19T08:37 Calendar date and local time (extended) %Y%jT%H%MZ => 2007323T0837Z Ordinal date and UTC of day (basic) %Y-%jT%RZ => 2007-323T08:37Z Ordinal date and UTC of day (extended) %GW%V%uT%H%M%z => 2007W471T0837-0600 Week date and local time and difference from UTC (basic) %G-W%V-%uT%R%:z => 2007-W47-1T08:37-06:00 Week date and local time and difference from UTC (extended)
Readable strftime
%a - The abbreviated weekday name (“Sun”)
%A - The full weekday name (“Sunday”)
%b - The abbreviated month name (“Jan”)
%B - The full month name (“January”)
%c - The preferred local date and time representation
%d - Day of the month (01..31) %H - Hour of the day, 24-hour clock (00..23)
%I - Hour of the day, 12-hour clock (01..12)
%j - Day of the year (001..366)
%m - Month of the year (01..12) %M - Minute of the hour (00..59)
%p - Meridian indicator (“AM” or “PM”)
%S - Second of the minute (00..60)
%U - Week number of the current year, starting with the first Sunday as the first day of the first week (00..53)
%W - Week number of the current year, starting with the first Monday as the first day of the first week (00..53)
%w - Day of the week (Sunday is 0, 0..6)
%x - Preferred representation for the date alone, no time
%X - Preferred representation for the time alone, no date
%y - Year without a century (00..99) %Y - Year with century
%Z - Time zone name %% - Literal “%” character t = Time.now t.strftime(“Printed on %m/%d/%Y”) #=> “Printed on 04/09/2003” t.strftime(“at %I:%M%p”) #=> “at 08:56AM”
Hour with/without preceding zero
One gotcha is the difference between the hour in 12 hour time with and without a preceding zero. In some fonts they look the same.
With preceding zero (capital I)
Time.now.strftime("%I:%M") # => 05:21
Without preceding zero (lowercase L)
Time.now.strftime("%l:%M") # => 5:21
Rmoving preceding 0's
In most *nix system, adding a - after the % will remove preceding 0s.
So %-d for a single digit day, or %-I for a single digit hour, etc.
Complete Formatting Codes
NOTE: Some of these seem only to work for DateTime (e.g. %L, %N)
%a - The abbreviated weekday name (“Sun”)
%A - The full weekday name (“Sunday”)
%b - The abbreviated month name (“Jan”)
%B - The full month name (“January”)
%c - The preferred local date and time representation
%C - Century (20 in 2009)
%d - Day of the month (01..31)
%D - Date (%m/%d/%y)
%e - Day of the month, blank-padded ( 1..31)
%F - Equivalent to %Y-%m-%d (the ISO 8601 date format)
%h - Equivalent to %b
%H - Hour of the day, 24-hour clock (00..23)
%I - Hour of the day, 12-hour clock (01..12)
%j - Day of the year (001..366)
%k - hour, 24-hour clock, blank-padded ( 0..23)
%l - hour, 12-hour clock, blank-padded ( 0..12)
%L - Millisecond of the second (000..999)
%m - Month of the year (01..12)
%M - Minute of the hour (00..59)
%n - Newline (n)
%N - Fractional seconds digits, default is 9 digits (nanosecond)
-
%3N millisecond (3 digits)
-
%6N microsecond (6 digits)
-
%9N nanosecond (9 digits)
%p - Meridian indicator (“AM” or “PM”)
%P - Meridian indicator (“am” or “pm”)
%r - time, 12-hour (same as %I:%M:%S %p)
%R - time, 24-hour (%H:%M)
%s - Number of seconds since 1970-01-01 00:00:00 UTC.
%S - Second of the minute (00..60)
%t - Tab character (t)
%T - time, 24-hour (%H:%M:%S)
%u - Day of the week as a decimal, Monday being 1. (1..7)
%U - Week number of the current year, starting with the first Sunday as the first day of the first week (00..53)
%v - VMS date (%e-%b-%Y)
%V - Week number of year according to ISO 8601 (01..53)
%W - Week number of the current year, starting with the first Monday as the first day of the first week (00..53)
%w - Day of the week (Sunday is 0, 0..6)
%x - Preferred representation for the date alone, no time
%X - Preferred representation for the time alone, no date
%y - Year without a century (00..99)
%Y - Year with century
%z - Time zone as hour offset from UTC (e.g. +0900)
%% - Literal “%” character
t = Time.now #=> 2007-11-19 08:37:48 -0600 t.strftime("Printed on %m/%d/%Y") #=> "Printed on 11/19/2007" t.strftime("at %I:%M%p") #=> "at 08:37AM"
OUTDATED!!!
Man, this stuff is so outdated. Be very careful using anything from here. A lot has changed since Ruby 1.9.
You’ll want to look at the updated docs, like here for Ruby 2.5.1:
ruby-doc.org/core-2.5.1/Time.html#method-i-strftime
They really should just take this site down if they’re not going to keep it updated. Probably does more harm than good now.
see also – similar methods
See also DateTime#strftime and Date#strftime . (They work similarly, but have different APIdock notes.)