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This manual page is part of the POSIX Programmer's Manual. The Linux implementation of
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NAME
strptime — date and time conversion
SYNOPSIS
#include <time.h>
char *strptime(const char *restrict buf, const char *restrict format,
struct tm *restrict tm);
DESCRIPTION
The strptime() function shall convert the character string pointed to by buf to values
which are stored in the tm structure pointed to by tm, using the format specified by
format.
The format is composed of zero or more directives. Each directive is composed of one of
the following: one or more white-space characters (as specified by isspace()); an ordinary
character (neither '%' nor a white-space character); or a conversion specification.
Each conversion specification is introduced by the '%' character after which the following
appear in sequence:
* An optional flag, the zero character ('0') or the <plus-sign> character ('+'), which
is ignored.
* An optional field width. If a field width is specified, it shall be interpreted as a
string of decimal digits that will determine the maximum number of bytes converted for
the conversion rather than the number of bytes specified below in the description of
the conversion specifiers.
* An optional E or O modifier.
* A terminating conversion specifier character that indicates the type of conversion to
be applied.
The conversions are determined using the LC_TIME category of the current locale. The
application shall ensure that there is white-space or other non-alphanumeric characters
between any two conversion specifications unless all of the adjacent conversion
specifications convert a known, fixed number of characters. In the following list, the
maximum number of characters scanned (excluding the one matching the next directive) is as
follows:
* If a maximum field width is specified, then that number
* Otherwise, the pattern "{x}" indicates that the maximum is x
* Otherwise, the pattern "[x,y]" indicates that the value shall fall within the range
given (both bounds being inclusive), and the maximum number of characters scanned
shall be the maximum required to represent any value in the range without leading
zeros and without a leading <plus-sign>
The following conversion specifiers are supported.
The results are unspecified if a modifier is specified with a flag or with a minimum field
width, or if a field width is specified for any conversion specifier other than C or Y.
a The day of the week, using the locale's weekday names; either the abbreviated or
full name may be specified.
A Equivalent to %a.
b The month, using the locale's month names; either the abbreviated or full name may
be specified.
B Equivalent to %b.
c Replaced by the locale's appropriate date and time representation.
C All but the last two digits of the year {2}; leading zeros shall be permitted but
shall not be required. A leading '+' or '-' character shall be permitted before
any leading zeros but shall not be required.
d The day of the month [01,31]; leading zeros shall be permitted but shall not be
required.
D The date as %m/%d/%y.
e Equivalent to %d.
h Equivalent to %b.
H The hour (24-hour clock) [00,23]; leading zeros shall be permitted but shall not
be required.
I The hour (12-hour clock) [01,12]; leading zeros shall be permitted but shall not
be required.
j The day number of the year [001,366]; leading zeros shall be permitted but shall
not be required.
m The month number [01,12]; leading zeros shall be permitted but shall not be
required.
M The minute [00,59]; leading zeros shall be permitted but shall not be required.
n Any white space.
p The locale's equivalent of a.m. or p.m.
r 12-hour clock time using the AM/PM notation if t_fmt_ampm is not an empty string
in the LC_TIME portion of the current locale; in the POSIX locale, this shall be
equivalent to %I:%M:%S %p.
R The time as %H:%M.
S The seconds [00,60]; leading zeros shall be permitted but shall not be required.
t Any white space.
T The time as %H:%M:%S.
U The week number of the year (Sunday as the first day of the week) as a decimal
number [00,53]; leading zeros shall be permitted but shall not be required.
w The weekday as a decimal number [0,6], with 0 representing Sunday.
W The week number of the year (Monday as the first day of the week) as a decimal
number [00,53]; leading zeros shall be permitted but shall not be required.
x The date, using the locale's date format.
X The time, using the locale's time format.
y The last two digits of the year. When format contains neither a C conversion
specifier nor a Y conversion specifier, values in the range [69,99] shall refer to
years 1969 to 1999 inclusive and values in the range [00,68] shall refer to years
2000 to 2068 inclusive; leading zeros shall be permitted but shall not be
required. A leading '+' or '-' character shall be permitted before any leading
zeros but shall not be required.
Note: It is expected that in a future version of this standard the default
century inferred from a 2-digit year will change. (This would apply to
all commands accepting a 2-digit year as input.)
Y The full year {4}; leading zeros shall be permitted but shall not be required. A
leading '+' or '-' character shall be permitted before any leading zeros but shall
not be required.
% Replaced by %.
Modified Conversion Specifiers
Some conversion specifiers can be modified by the E and O modifier characters to indicate
that an alternative format or specification should be used rather than the one normally
used by the unmodified conversion specifier. If the alternative format or specification
does not exist in the current locale, the behavior shall be as if the unmodified
conversion specification were used.
%Ec The locale's alternative appropriate date and time representation.
%EC The name of the base year (period) in the locale's alternative representation.
%Ex The locale's alternative date representation.
%EX The locale's alternative time representation.
%Ey The offset from %EC (year only) in the locale's alternative representation.
%EY The full alternative year representation.
%Od The day of the month using the locale's alternative numeric symbols; leading zeros
shall be permitted but shall not be required.
%Oe Equivalent to %Od.
%OH The hour (24-hour clock) using the locale's alternative numeric symbols.
%OI The hour (12-hour clock) using the locale's alternative numeric symbols.
%Om The month using the locale's alternative numeric symbols.
%OM The minutes using the locale's alternative numeric symbols.
%OS The seconds using the locale's alternative numeric symbols.
%OU The week number of the year (Sunday as the first day of the week) using the
locale's alternative numeric symbols.
%Ow The number of the weekday (Sunday=0) using the locale's alternative numeric
symbols.
%OW The week number of the year (Monday as the first day of the week) using the
locale's alternative numeric symbols.
%Oy The year (offset from %C) using the locale's alternative numeric symbols.
A conversion specification composed of white-space characters is executed by scanning
input up to the first character that is not white-space (which remains unscanned), or
until no more characters can be scanned.
A conversion specification that is an ordinary character is executed by scanning the next
character from the buffer. If the character scanned from the buffer differs from the one
comprising the directive, the directive fails, and the differing and subsequent characters
remain unscanned.
A series of conversion specifications composed of %n, %t, white-space characters, or any
combination is executed by scanning up to the first character that is not white space
(which remains unscanned), or until no more characters can be scanned.
Any other conversion specification is executed by scanning characters until a character
matching the next directive is scanned, or until no more characters can be scanned. These
characters, except the one matching the next directive, are then compared to the locale
values associated with the conversion specifier. If a match is found, values for the
appropriate tm structure members are set to values corresponding to the locale
information. Case is ignored when matching items in buf such as month or weekday names. If
no match is found, strptime() fails and no more characters are scanned.
RETURN VALUE
Upon successful completion, strptime() shall return a pointer to the character following
the last character parsed. Otherwise, a null pointer shall be returned.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
Convert a Date-Plus-Time String to Broken-Down Time and Then into Seconds
The following example demonstrates the use of strptime() to convert a string into broken-
down time. The broken-down time is then converted into seconds since the Epoch using
mktime().
#include <time.h>
...
struct tm tm;
time_t t;
if (strptime("6 Dec 2001 12:33:45", "%d %b %Y %H:%M:%S", &tm) == NULL)
/* Handle error */;
printf("year: %d; month: %d; day: %d;\n",
tm.tm_year, tm.tm_mon, tm.tm_mday);
printf("hour: %d; minute: %d; second: %d\n",
tm.tm_hour, tm.tm_min, tm.tm_sec);
printf("week day: %d; year day: %d\n", tm.tm_wday, tm.tm_yday);
tm.tm_isdst = -1; /* Not set by strptime(); tells mktime()
to determine whether daylight saving time
is in effect */
t = mktime(&tm);
if (t == -1)
/* Handle error */;
printf("seconds since the Epoch: %ld\n", (long) t);"
APPLICATION USAGE
Several ``equivalent to'' formats and the special processing of white-space characters are
provided in order to ease the use of identical format strings for strftime() and
strptime().
It should be noted that dates constructed by the strftime() function with the %Y or %C%y
conversion specifiers may have values larger than 9999. If the strptime() function is used
to read such values using %C%y or %Y, the year values will be truncated to four digits.
Applications should use %+w%y or %+xY with w and x set large enough to contain the full
value of any years that will be printed or scanned.
See also the APPLICATION USAGE section in strftime().
It is unspecified whether multiple calls to strptime() using the same tm structure will
update the current contents of the structure or overwrite all contents of the structure.
Conforming applications should make a single call to strptime() with a format and all data
needed to completely specify the date and time being converted.
RATIONALE
See the RATIONALE section for strftime().
FUTURE DIRECTIONS
None.
SEE ALSO
fprintf(), fscanf(), strftime(), time()
The Base Definitions volume of POSIX.1‐2017, <time.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1-2017, Standard for Information Technology -- Portable Operating System Interface
(POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by
the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard is the referee document. The
original Standard can be obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page are most likely to have
been introduced during the conversion of the source files to man page format. To report
such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .