strftime(3C)

NAME

strftime, cftime, ascftime − convert date and time to string

SYNOPSIS

#include <time.h>

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

int cftime(char ∗s, char ∗format, const time_t ∗clock);

int ascftime(char ∗s, const char ∗format, const struct tm ∗timeptr);

DESCRIPTION

strftime(), ascftime(), and cftime() place characters into the array pointed to by s as controlled by the string pointed to by format. The format string consists of zero or more directives and ordinary characters. All ordinary characters (including the terminating null character) are copied unchanged into the array. For strftime(), no more than maxsize characters are placed into the array.

If format is (char ∗)0, then the locale’s default format is used. For strftime() the default format is the same as “%c”, for cftime() and ascftime() the default format is the same as %C. cftime() and ascftime() first try to use the value of the environment variable CFTIME, and if that is undefined or empty, the default format is used.

Each directive is replaced by appropriate characters as described in the following list. The appropriate characters are determined by the LC_TIME category of the program’s locale and by the values contained in the structure pointed to by timeptr for strftime() and ascftime(), and by the time represented by clock for cftime().

%% same as the “percent” character (%)

%a locale’s abbreviated weekday name

%A locale’s full weekday name

%b locale’s abbreviated month name

%B locale’s full month name

%c locale’s appropriate date and time representation

%C locale’s date and time representation as produced by date(1)

%d day of month ( 01 - 31 )

%D date as %m/%d/%y

%e day of month (1-31; single digits are preceded by a space)

%h locale’s abbreviated month name.

%H hour ( 00 - 23 )

%I hour ( 01 - 12 )

%j day number of year ( 001 - 366 )

%m month number ( 01 - 12 )

%M minute ( 00 - 59 )

%n same as \n

%p locale’s equivalent of either AM or PM

%r time as %I:%M:%S [AM|PM]

%R time as %H:%M

%S seconds ( 00 - 61 ), allows for leap seconds

%t insert a tab

%T time as %H:%M:%S

%U week number of year ( 00 - 53 ), Sunday is the first day of week 1

%w weekday number ( 0 - 6 ), Sunday = 0

%W week number of year ( 00 - 53 ), Monday is the first day of week 1

%x locale’s appropriate date representation

%X locale’s appropriate time representation

%y year within century ( 00 - 99 )

%Y year as ccyy ( for example 1986)

%Z time zone name or no characters if no time zone exists

The difference between %U and %W lies in which day is counted as the first of the week. Week number 01 is the first week in January starting with a Sunday for %U or a Monday for %W. Week number 00 contains those days before the first Sunday or Monday in January for %U and %W, respectively.

If the total number of resulting characters including the terminating null character is not more than maxsize, strftime(), cftime() and ascftime() return the number of characters placed into the array pointed to by s not including the terminating null character. Otherwise, zero is returned and the contents of the array are indeterminate.

Selecting the Output’s Language

By default, the output of strftime(), cftime(), and ascftime() appear in US English. The user can request that the output of strftime(), cftime() or ascftime() be in a specific language by setting the locale for category LC_TIME in setlocale().

Timezone

The timezone is taken from the environment variable TZ (see ctime(3C) for a description of TZ).

EXAMPLES

The example illustrates the use of strftime(). It shows what the string in str would look like if the structure pointed to by tmptr contains the values corresponding to Thursday, August 28, 1986 at 12:44:36 in New Jersey.

strftime (str, strsize, "%A %b %d %j", tmptr)

This results in str containing "Thursday Aug 28 240".

FILES

/usr/lib/locale/language/LC_TIME − file containing locale specific date and time information

NOTE

cftime() and ascftime() are obsolete. strftime() should be used instead.

SunOS 5.1/SPARC — Last change: 13 Jul 1990

Museum

Related Articles