преобразование даты и времени (date and time conversion)
Описание (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.
