strftime
Defined in header
<time.h>
|
||
(until C99) | ||
(since C99) | ||
Converts the date and time information from a given calendar time tp to a null-terminated multibyte character string str according to format string format . Up to count bytes are written.
Parameters
str | - | pointer to the first element of the char array for output |
count | - | maximum number of bytes to write |
format | - | pointer to a null-terminated multibyte character string specifying the format of conversion |
tp | - | pointer to a struct tm object specifying the time to format |
Format string
The format string consists of zero or more conversion specifiers and ordinary characters (except
%
). All ordinary characters, including the terminating null character, are copied to the output string without modification. Each conversion specification begins with
%
character, optionally followed by
E
or
O
modifier (ignored if unsupported by the locale), followed by the character that determines the behavior of the specifier. The following format specifiers are available:
Conversion
specifier |
Explanation | Used fields |
---|---|---|
%
|
writes literal
%
. The full conversion specification must be
%%
.
|
|
n
(C99) |
writes newline character | |
t
(C99) |
writes horizontal tab character | |
Year | ||
Y
|
writes year as a decimal number, e.g. 2017 |
tm_year
|
EY
(C99) |
writes year in the alternative representation, e.g.平成23年 (year Heisei 23) instead of 2011年 (year 2011) in ja_JP locale |
tm_year
|
y
|
writes last 2 digits of
year
as a decimal number (range
[00,99]
)
|
tm_year
|
Oy
(C99) |
writes last 2 digits of year using the alternative numeric system, e.g. 十一 instead of 11 in ja_JP locale |
tm_year
|
Ey
(C99) |
writes
year
as offset from locale's alternative calendar period
%EC
(locale-dependent)
|
tm_year
|
C
(C99) |
writes first 2 digits of
year
as a decimal number (range
[00,99]
)
|
tm_year
|
EC
(C99) |
writes name of the base year (period) in the locale's alternative representation, e.g. 平成 (Heisei era) in ja_JP |
tm_year
|
G
(C99) |
writes
ISO 8601 week-based year
, i.e. the year that contains the specified week.
In ISO 8601 weeks begin with Monday and the first week of the year must satisfy the following requirements:
|
tm_year
,
tm_wday
,
tm_yday
|
g
(C99) |
writes last 2 digits of
ISO 8601 week-based year
, i.e. the year that contains the specified week (range
[00,99]
).
In ISO 8601 weeks begin with Monday and the first week of the year must satisfy the following requirements:
|
tm_year
,
tm_wday
,
tm_yday
|
Month | ||
b
|
writes
abbreviated month
name, e.g.
Oct
(locale dependent)
|
tm_mon
|
Ob
(C23) |
writes abbreviated month name in the locale's alternative representation |
tm_mon
|
h
(C99) |
synonym of
b
|
tm_mon
|
B
|
writes
full month
name, e.g.
October
(locale dependent)
|
tm_mon
|
OB
(C23) |
writes appropriate full month name in the locale's alternative representation |
tm_mon
|
m
|
writes
month
as a decimal number (range
[01,12]
)
|
tm_mon
|
Om
(C99) |
writes month using the alternative numeric system, e.g. 十二 instead of 12 in ja_JP locale |
tm_mon
|
Week | ||
U
|
writes
week of the year
as a decimal number (Sunday is the first day of the week) (range
[00,53]
)
|
tm_year
,
tm_wday
,
tm_yday
|
OU
(C99) |
writes
week of the year
, as by
%U
, using the alternative numeric system, e.g. 五十二 instead of 52 in ja_JP locale
|
tm_year
,
tm_wday
,
tm_yday
|
W
|
writes
week of the year
as a decimal number (Monday is the first day of the week) (range
[00,53]
)
|
tm_year
,
tm_wday
,
tm_yday
|
OW
(C99) |
writes
week of the year
, as by
%W
, using the alternative numeric system, e.g. 五十二 instead of 52 in ja_JP locale
|
tm_year
,
tm_wday
,
tm_yday
|
V
(C99) |
writes
ISO 8601 week of the year
(range
[01,53]
).
In ISO 8601 weeks begin with Monday and the first week of the year must satisfy the following requirements:
|
tm_year
,
tm_wday
,
tm_yday
|
OV
(C99) |
writes
week of the year
, as by
%V
, using the alternative numeric system, e.g. 五十二 instead of 52 in ja_JP locale
|
tm_year
,
tm_wday
,
tm_yday
|
Day of the year/month | ||
j
|
writes
day of the year
as a decimal number (range
[001,366]
)
|
tm_yday
|
d
|
writes
day of the month
as a decimal number (range
[01,31]
)
|
tm_mday
|
Od
(C99) |
writes zero-based
day of the month
using the alternative numeric system, e.g. 二十七 instead of 27 in ja_JP locale
Single character is preceded by a space. |
tm_mday
|
e
(C99) |
writes
day of the month
as a decimal number (range
[1,31]
).
Single digit is preceded by a space. |
tm_mday
|
Oe
(C99) |
writes one-based
day of the month
using the alternative numeric system, e.g. 二十七 instead of 27 in ja_JP locale
Single character is preceded by a space. |
tm_mday
|
Day of the week | ||
a
|
writes
abbreviated weekday
name, e.g.
Fri
(locale dependent)
|
tm_wday
|
A
|
writes
full weekday
name, e.g.
Friday
(locale dependent)
|
tm_wday
|
w
|
writes
weekday
as a decimal number, where Sunday is
0
(range
[0-6]
)
|
tm_wday
|
Ow
(C99) |
writes
weekday
, where Sunday is
0
, using the alternative numeric system, e.g. 二 instead of 2 in ja_JP locale
|
tm_wday
|
u
(C99) |
writes
weekday
as a decimal number, where Monday is
1
(ISO 8601 format) (range
[1-7]
)
|
tm_wday
|
Ou
(C99) |
writes
weekday
, where Monday is
1
, using the alternative numeric system, e.g. 二 instead of 2 in ja_JP locale
|
tm_wday
|
Hour, minute, second | ||
H
|
writes
hour
as a decimal number, 24 hour clock (range
[00-23]
)
|
tm_hour
|
OH
(C99) |
writes hour from 24-hour clock using the alternative numeric system, e.g. 十八 instead of 18 in ja_JP locale |
tm_hour
|
I
|
writes
hour
as a decimal number, 12 hour clock (range
[01,12]
)
|
tm_hour
|
OI
(C99) |
writes hour from 12-hour clock using the alternative numeric system, e.g. 六 instead of 06 in ja_JP locale |
tm_hour
|
M
|
writes
minute
as a decimal number (range
[00,59]
)
|
tm_min
|
OM
(C99) |
writes minute using the alternative numeric system, e.g. 二十五 instead of 25 in ja_JP locale |
tm_min
|
S
|
writes
second
as a decimal number (range
[00,60]
)
|
tm_sec
|
OS
(C99) |
writes second using the alternative numeric system, e.g. 二十四 instead of 24 in ja_JP locale |
tm_sec
|
Other | ||
c
|
writes
standard date and time string
, e.g.
Sun Oct 17 04:41:13 2010
(locale dependent)
|
all |
Ec
(C99) |
writes alternative date and time string , e.g. using 平成23年 (year Heisei 23) instead of 2011年 (year 2011) in ja_JP locale | all |
x
|
writes localized date representation (locale dependent) | all |
Ex
(C99) |
writes alternative date representation , e.g. using 平成23年 (year Heisei 23) instead of 2011年 (year 2011) in ja_JP locale | all |
X
|
writes localized time representation , e.g. 18:40:20 or 6:40:20 PM (locale dependent) | all |
EX
(C99) |
writes alternative time representation (locale dependent) | all |
D
(C99) |
equivalent to "%m/%d/%y" |
tm_mon
,
tm_mday
,
tm_year
|
F
(C99) |
equivalent to "%Y-%m-%d" (the ISO 8601 date format) |
tm_mon
,
tm_mday
,
tm_year
|
r
(C99) |
writes localized 12-hour clock time (locale dependent) |
tm_hour
,
tm_min
,
tm_sec
|
R
(C99) |
equivalent to "%H:%M" |
tm_hour
,
tm_min
|
T
(C99) |
equivalent to "%H:%M:%S" (the ISO 8601 time format) |
tm_hour
,
tm_min
,
tm_sec
|
p
|
writes localized a.m. or p.m. (locale dependent) |
tm_hour
|
z
(C99) |
writes
offset from UTC
in the ISO 8601 format (e.g.
-0430
), or no characters if the time zone information is not available
|
tm_isdst
|
Z
|
writes locale-dependent time zone name or abbreviation , or no characters if the time zone information is not available |
tm_isdst
|
Return value
The number of bytes written into the character array pointed to by str not including the terminating ' \0 ' on success. If count was reached before the entire string could be stored, 0 is returned and the contents are indeterminate.
Example
#include <locale.h> #include <stdio.h> #include <time.h> int main(void) { char buff[70]; struct tm my_time = { .tm_year=112, // = year 2012 .tm_mon=9, // = 10th month .tm_mday=9, // = 9th day .tm_hour=8, // = 8 hours .tm_min=10, // = 10 minutes .tm_sec=20 // = 20 secs }; if (strftime(buff, sizeof buff, "%A %c", &my_time)) puts(buff); else puts("strftime failed"); setlocale(LC_TIME, "el_GR.utf8"); if (strftime(buff, sizeof buff, "%A %c", &my_time)) puts(buff); else puts("strftime failed"); }
Possible output:
Sunday Sun Oct 9 08:10:20 2012 Κυριακή Κυρ 09 Οκτ 2012 08:10:20 πμ EST
References
- C23 standard (ISO/IEC 9899:2024):
-
- 7.27.3.5 The strftime function (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
-
- 7.27.3.5 The strftime function (p: 288-291)
- C11 standard (ISO/IEC 9899:2011):
-
- 7.27.3.5 The strftime function (p: 394-397)
- C99 standard (ISO/IEC 9899:1999):
-
- 7.23.3.5 The strftime function (p: 343-347)
- C89/C90 standard (ISO/IEC 9899:1990):
-
- 4.12.3.5 The strftime function
See also
(deprecated in C23)
(C11)
|
converts a
tm
object to a textual representation
(function) |
(deprecated in C23)
(C11)
|
converts a
time_t
object to a textual representation
(function) |
(C95)
|
converts a
tm
object to custom wide string textual representation
(function) |
C++ documentation
for
strftime
|