Module chrono::format::strftime [−][src]
strftime
/strptime
inspired date and time formatting syntax.
Specifiers
The following specifiers are available both to formatting and parsing.
Spec.  Example  Description 

DATE SPECIFIERS:  
%Y  2001  The full proleptic Gregorian year, zeropadded to 4 digits. [1] 
%C  20  The proleptic Gregorian year divided by 100, zeropadded to 2 digits. [2] 
%y  01  The proleptic Gregorian year modulo 100, zeropadded to 2 digits. [2] 
%m  07  Month number (0112), zeropadded to 2 digits. 
%b  Jul  Abbreviated month name. Always 3 letters. 
%B  July  Full month name. Also accepts corresponding abbreviation in parsing. 
%h  Jul  Same to %b . 
%d  08  Day number (0131), zeropadded to 2 digits. 
%e  8  Same to %d but spacepadded. Same to %_d . 
%a  Sun  Abbreviated weekday name. Always 3 letters. 
%A  Sunday  Full weekday name. Also accepts corresponding abbreviation in parsing. 
%w  0  Sunday = 0, Monday = 1, ..., Saturday = 6. 
%u  7  Monday = 1, Tuesday = 2, ..., Sunday = 7. (ISO 8601) 
%U  28  Week number starting with Sunday (0053), zeropadded to 2 digits. [3] 
%W  27  Same to %U , but week 1 starts with the first Monday in that year instead. 
%G  2001  Same to %Y but uses the year number in ISO 8601 week date. [4] 
%g  01  Same to %y but uses the year number in ISO 8601 week date. [4] 
%V  27  Same to %U but uses the week number in ISO 8601 week date (0153). [4] 
%j  189  Day of the year (001366), zeropadded to 3 digits. 
%D  07/08/01  Monthdayyear format. Same to %m/%d/%y . 
%x  07/08/01  Same to %D . 
%F  20010708  Yearmonthday format (ISO 8601). Same to %Y%m%d . 
%v  8Jul2001  Daymonthyear format. Same to %e%b%Y . 
TIME SPECIFIERS:  
%H  00  Hour number (0023), zeropadded to 2 digits. 
%k  0  Same to %H but spacepadded. Same to %_H . 
%I  12  Hour number in 12hour clocks (0112), zeropadded to 2 digits. 
%l  12  Same to %I but spacepadded. Same to %_I . 
%P  am  am or pm in 12hour clocks. 
%p  AM  AM or PM in 12hour clocks. 
%M  34  Minute number (0059), zeropadded to 2 digits. 
%S  60  Second number (0060), zeropadded to 2 digits. [5] 
%f  026490000  The fractional seconds (in nanoseconds) since last whole second. [8] 
%.f  .026490  Similar to .%f but leftaligned. These all consume the leading dot. [8] 
%.3f  .026  Similar to .%f but leftaligned but fixed to a length of 3. [8] 
%.6f  .026490  Similar to .%f but leftaligned but fixed to a length of 6. [8] 
%.9f  .026490000  Similar to .%f but leftaligned but fixed to a length of 9. [8] 
%3f  026  Similar to %.3f but without the leading dot. [8] 
%6f  026490  Similar to %.6f but without the leading dot. [8] 
%9f  026490000  Similar to %.9f but without the leading dot. [8] 
%R  00:34  Hourminute format. Same to %H:%M . 
%T  00:34:60  Hourminutesecond format. Same to %H:%M:%S . 
%X  00:34:60  Same to %T . 
%r  12:34:60 AM  Hourminutesecond format in 12hour clocks. Same to %I:%M:%S %p . 
TIME ZONE SPECIFIERS:  
%Z  ACST  Formatting only: Local time zone name. 
%z  +0930  Offset from the local time to UTC (with UTC being +0000 ). 
%:z  +09:30  Same to %z but with a colon. 
%#z  +09  Parsing only: Same to %z but allows minutes to be missing or present. 
DATE & TIME SPECIFIERS:  
%c  Sun Jul 8 00:34:60 2001  ctime date & time format. Same to %a %b %e %T %Y sans \n . 
%+  20010708T00:34:60.026490+09:30  ISO 8601 / RFC 3339 date & time format. [6] 
%s  994518299  UNIX timestamp, the number of seconds since 19700101 00:00 UTC. [7] 
SPECIAL SPECIFIERS:  
%t  Literal tab (\t ).  
%n  Literal newline (\n ).  
%%  Literal percent sign. 
It is possible to override the default padding behavior of numeric specifiers %?
.
This is not allowed for other specifiers and will result in the BAD_FORMAT
error.
Modifier  Description 

%?  Suppresses any padding including spaces and zeroes. (e.g. %j = 012 , %j = 12 ) 
%_?  Uses spaces as a padding. (e.g. %j = 012 , %_j = 12 ) 
%0?  Uses zeroes as a padding. (e.g. %e = 9 , %0e = 09 ) 
Notes:

%Y
: Negative years are allowed in formatting but not in parsing. 
%C
,%y
: This is floor division, so 100 BCE (year number 99) will print1
and99
respectively. 
%U
: Week 1 starts with the first Sunday in that year. It is possible to have week 0 for days before the first Sunday. 
%G
,%g
,%V
: Week 1 is the first week with at least 4 days in that year. Week 0 does not exist, so this should be used with%G
or%g
. 
%S
: It accounts for leap seconds, so60
is possible. 
%+
: Same to%Y%m%dT%H:%M:%S%.f%:z
, i.e. 0, 3, 6 or 9 fractional digits for seconds and colons in the time zone offset.The typical
strftime
implementations have different (and localedependent) formats for this specifier. While Chrono's format for%+
is far more stable, it is best to avoid this specifier if you want to control the exact output. 
%s
: This is not padded and can be negative. For the purpose of Chrono, it only accounts for nonleap seconds so it slightly differs from ISO Cstrftime
behavior. 
%f
,%.f
,%.3f
,%.6f
,%.9f
,%3f
,%6f
,%9f
:The default
%f
is rightaligned and always zeropadded to 9 digits for the compatibility with glibc and others, so it always counts the number of nanoseconds since the last whole second. E.g. 7ms after the last second will print007000000
, and parsing7000000
will yield the same.The variant
%.f
is leftaligned and print 0, 3, 6 or 9 fractional digits according to the precision. E.g. 70ms after the last second under%.f
will print.070
(note: not.07
), and parsing.07
,.070000
etc. will yield the same. Note that they can print or read nothing if the fractional part is zero or the next character is not.
.The variant
%.3f
,%.6f
and%.9f
are leftaligned and print 3, 6 or 9 fractional digits according to the number precedingf
. E.g. 70ms after the last second under%.3f
will print.070
(note: not.07
), and parsing.07
,.070000
etc. will yield the same. Note that they can read nothing if the fractional part is zero or the next character is not.
however will print with the specified length.The variant
%3f
,%6f
and%9f
are leftaligned and print 3, 6 or 9 fractional digits according to the number precedingf
, but without the leading dot. E.g. 70ms after the last second under%3f
will print070
(note: not07
), and parsing07
,070000
etc. will yield the same. Note that they can read nothing if the fractional part is zero.
Structs
StrftimeItems 
Parsing iterator for 