The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.

#### NAME

> strptime - date and time conversion

#### SYNOPSIS

> ``[XSI] #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 composed of a `'%'` character followed by a conversion character which specifies the replacement required. The application shall ensure that there is white-space or other non-alphanumeric characters between any two conversion specifications. The following conversion specifications are supported:

> `%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`
>   The century number [00,99]; leading zeros are permitted but not required.
> `%d`
>   The day of the month [01,31]; leading zeros are permitted but not 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 are permitted but not required.
> `%I`
>   The hour (12-hour clock) [01,12]; leading zeros are permitted but not required.
> `%j`
>   The day number of the year [001,366]; leading zeros are permitted but not required.
> `%m`
>   The month number [01,12]; leading zeros are permitted but not required.
> `%M`
>   The minute [00,59]; leading zeros are permitted but not 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 are permitted but not 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 are permitted but not required.
> `%w`
>   The weekday as a decimal number [0,6], with 0 representing Sunday; leading zeros are permitted but not required.
> `%W`
>   The week number of the year (Monday as the first day of the week) as a decimal number [00,53]; leading zeros are permitted but not required.
> `%x`
>   The date, using the locale's date format.
> `%X`
>   The time, using the locale's time format.
> `%y`
>   The year within century. When a century is not otherwise specified, 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.
>   Note:
>     It is expected that in a future version of IEEE Std 1003.1-2001 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 year, including the century (for example, 1988).
> `%%`
>   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 are permitted but not 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 Data-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().

> Applications should use `%Y` (4-digit years) in preference to `%y` (2-digit years).

> 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

> None.

#### FUTURE DIRECTIONS

> The strptime() function is expected to be mandatory in the next version of this volume of IEEE Std 1003.1-2001.

#### SEE ALSO

> scanf(), strftime(), time() , the Base Definitions volume of IEEE Std 1003.1-2001, <time.h>

#### CHANGE HISTORY

> First released in Issue 4.

#### Issue 5

> Moved from ENHANCED I18N to BASE.

> The [ENOSYS] error is removed.

> The exact meaning of the `%y` and `%Oy` specifiers is clarified in the DESCRIPTION.

#### Issue 6

> The Open Group Corrigendum U033/5 is applied. The `%r` specifier description is reworded.

> The DESCRIPTION is updated to avoid use of the term "must" for application requirements.

> The restrict keyword is added to the strptime() prototype for alignment with the ISO/IEC 9899:1999 standard.

> The Open Group Corrigendum U047/2 is applied.

> The DESCRIPTION is updated to use the terms "conversion specifier" and "conversion specification" for consistency with strftime().

> IEEE Std 1003.1-2001/Cor 2-2004, item XSH/TC2/D6/133 is applied, adding the example to the EXAMPLES section.

End of informative text.

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