STRFTIME

NAME

SYNOPSIS

#include <sys/types.h>
#include <time.h>

size_t strftime(char *s, size_t maxsize, const char *format,
        const struct tm *timeptr);

DESCRIPTION

The strftime function places characters into the array pointed to by s as controlled by the string pointed to by format. The format shall be a multibyte character sequence, beginning and ending in its initial shift state. The format string consists of zero or more conversion specifiers and ordinary multibyte characters. A conversion specifier consists of a % character followed by a character that determines the behavior of the conversion specifier. All ordinary multibyte characters (including the terminating null character) are copied unchanged into the array. If copying takes place between objects that overlap the behavior is undefined. No more than maxsize characters are placed into the array. Each conversion specifier is replaced by appropriate characters as described in the following list. The appropriate characters are determined by the LC_TIME category of the current locale and by the values contained in the structure pointed to by timeptr.

%a

is replaced by the locale's abbreviated weekday name.

%A

is replaced by the locale's full weekday name.

%b

is replaced by the locale's abbreviated month name.

%B

is replaced by the locale's full month name.

%c

is replaced by the locale's appropriate date and time representation.

%d

is replaced by the day of the month as a decimal number (01-31).

%H

is replaced by the hour (24-hour clock) as a decimal number (00-23).

%I

is replaced by the hour (12-hour clock) as a decimal number (01-12).

%j

is replaced by the day of the year as a decimal number (001-366).

%m

is replaced by the month as a decimal number (01-12).

%M

is replaced by the minute as a decimal number (00-59).

%p

is replaced by the locale's equivalent of the AM/PM designations associated with a 12-hour clock.

%S

is replaced by the second as a decimal number (00-60).

%U

is replaced by the week number of the year (the first Sunday as the first day of week 1) as a decimal number (00-53).

%w

is replaced by the weekday as a decimal number [0 (Sunday)-6].

%W

is replaced by the week number of the year (the first Monday as the first day of week 1) as a decimal number (00-53).

%x

is replaced by the locale's appropriate date representation.

%X

is replaced by the locale's appropriate time representation.

%y

is replaced by the year without century as a decimal number (00-99).

%Y

is replaced by the year with century as a decimal number.

%Z

is replaced by the time zone name or abbreviation, or by no characters if no time zone is determinable.

%%

is replaced by %.

If a conversion specifier is not one of the above, the behavior is undefined.  

RETURNS

NON-ANSI EXTENSIONS

%D

is equivalent to specifying %m/%d/%y.

%e

is replaced by the day of the month, padded with a blank if it is only one digit.

%h

is equivalent to %b, above.

%n

is replaced with a newline character (ASCII LF).

%r

is equivalent to specifying %I:%M:%S %p.

%R

is equivalent to specifying %H:%M.

%T

is equivalent to specifying %H:%M:%S.

%t

is replaced with a TAB character.

If SUNOS_EXT is defined when the routine is compiled, then the following additional conversions will be available. These are borrowed from the SunOS version of strftime.

%k

is replaced by the hour (24-hour clock) as a decimal number (0-23). Single digit numbers are padded with a blank.

%l

is replaced by the hour (12-hour clock) as a decimal number (1-12). Single digit numbers are padded with a blank.

POSIX 1003.2 EXTENSIONS

%C

The century, as a number between 00 and 99.

%u

is replaced by the weekday as a decimal number [1 (Monday)-7].

%V

is replaced by the week number of the year (the first Monday as the first day of week 1) as a decimal number (01-53). The method for determining the week number is as specified by ISO 8601 (to wit: if the week containing January 1 has four or more days in the new year, then it is week 1, otherwise it is the highest numbered week of the previous year (52 or 53) and the next week is week 1).

The text of the POSIX standard for the date utility describes %U and %W this way:

%U

is replaced by the week number of the year (the first Sunday as the first day of week 1) as a decimal number (00-53). All days in a new year preceding the first Sunday are considered to be in week 0.

%W

is replaced by the week number of the year (the first Monday as the first day of week 1) as a decimal number (00-53). All days in a new year preceding the first Monday are considered to be in week 0.

In addition, the alternate representations %Ec, %EC, %Ex, %Ey, %EY, %Od, %Oe, %OH, %OI, %Om, %OM, %OS, %Ou, %OU, %OV, %Ow, %OW, and %Oy are recognized, but their normal representations are used.  

VMS EXTENSIONS

%v

The date in VMS format (e.g. 20-JUN-1991).

MAIL HEADER EXTENSIONS

%z

The timezone offset in a +HHMM format (e.g. the format necessary to produce RFC-822/RFC-1036 date headers).

ISO DATE FORMAT EXTENSIONS

%G

is replaced by the year with century of the ISO week number (see %V, above) as a decimal number.

%g

is replaced by the year without century of the ISO week number, as a decimal number (00-99).

For example, January 1, 1993, is in week 53 of 1992. Thus, the year of its ISO week number is 1992, even though its year is 1993. Similarly, December 31, 1973, is in week 1 of 1974. Thus, the year of its ISO week number is 1974, even though its year is 1973.  

SEE ALSO

BUGS

The ``appropriate'' values used for %c, %x, are %X are those specified by the 1003.2 standard for the POSIX locale.  

CAVEATS

AUTHOR

Arnold Robbins

INTERNET: arnold@gnu.ai.mit.edu

ACKNOWLEDGEMENTS

Index

NAME

SYNOPSIS

DESCRIPTION

RETURNS

NON-ANSI EXTENSIONS

POSIX 1003.2 EXTENSIONS

VMS EXTENSIONS

MAIL HEADER EXTENSIONS

ISO DATE FORMAT EXTENSIONS

SEE ALSO

BUGS

CAVEATS

AUTHOR

ACKNOWLEDGEMENTS