Syntax
asctime(seconds, format)
Description
The asctime() function returns the formatted date/time of seconds since 1970-01-01 00:00:00 UTC.
If format is given, asctime() returns the date/time strings in the specified format.
If no format is given, the a default of “%a %b %d %H:%M:%S %Y” is used.
Format
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 no-padded (1..12)
%B - Full month name (January)
%b - Abbreviated month name (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)
%-j no-padded (1..366)
Time (Hour, Minute, Second, Subsecond):
%H - Hour of the day, 24-hour clock, zero-padded (00..23)
%-H no-padded (0..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)
%-I no-padded (1..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)
%-M no-padded (0..59)
%S - Second of the minute (00..60)
%-S no-padded (0..60)
%L - Millisecond of the second (000..999) %f - Microsecond of the second (000000..999999) %N - Nanosecond of the second (000000000..999999999)
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 - Time zone abbreviation (e.g. MST)
Weekday:
%A - Full weekday name (Sunday) %a - Abbreviated weekday name (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: 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 - Week-based year
%g - Last 2 digits of the week-based year (00..99)
%V - Week number of the week-based year (01..53)
%-V no-padded (1..53)
Week number: 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)
%-U no-padded (0..53)
%W - Week number of the year. The week starts with Monday. (00..53)
%-W no-padded (0..53)
Seconds since the Unix Epoch:
%s - Number of seconds since 1970-01-01 00:00:00 UTC. %Q - Number of milliseconds 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 - ISO 8601 date format (%Y-%m-%d) %v - VMS date (%e-%b-%Y) %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) %+ - date(1) (%a %b %e %H:%M:%S %Z %Y)
Example
raw_time=time()
default_output=asctime(raw_time)
printf("raw time is %d, default asctime() output is %s\n", raw_time, default_output)
output_with_format=asctime(raw_time, "Day is %A, Month is %B, Time is %X, Timezone is %Z")
printf("%s\n", output_with_format)
raw time is 1669923810, default asctime() output is Thu Dec 01 19:43:30 2022
Day is Thursday, Month is December, Time is 19:43:30, Timezone is GMT