STRPTIME(3) | Library Functions Manual | STRPTIME(3)

# NAME

`strptime` — converts a character string to a time value

# SYNOPSIS

`#include <time.h>`

char *
`strptime`(const char *buf, const char *format, struct tm *tm);

# DESCRIPTION

The `strptime` function parses the string buf according to the specified format and fills matching data into the structure tm (described in mktime(3)).

The format string consists of zero or more directives. A directive is composed of either one or more whitespace characters as defined by isspace(3), an ordinary character (neither ‘%’ nor a whitespace), or a conversion specification. A conversion specification consists of a percent sign (‘%’) followed by one or two conversion characters which specify the replacement required. There must be whitespace or other non-alphanumeric characters between any two conversion specifications.

The following conversion specifications are supported:

`%a`
  the day of week, using the locale's weekday names; either the abbreviated or full name may be specified.
`%A`
  the same as `%a`.
`%b`
  the month, using the locale's month names; either the abbreviated or full name may be specified.
`%B`
  the same as `%b`.
`%c`
  the date and time, using the locale's date and time format.
`%C`
  the century number [0,99]; leading zeros are permitted but not required. Note that the converted value is added to the current value of the tm_year field (in order that the "%y" conversion be useful).
`%d`
  the day of month [1,31]; leading zeros are permitted but not required.
`%D`
  the date as %m/%d/%y.
`%e`
  the day of month [1,31]; leading spaces or zeros are permitted but not required.
`%F`
  the date as %Y-%m-%d (the ISO 8601 date format).
`%g`
  the year corresponding to the ISO week number, without the century.
`%G`
  the year corresponding to the ISO week number, with the century.
`%h`
  the same as `%b`.
`%H`
  the hour (24-hour clock) [0,23]; leading zeros are permitted but not required.
`%I`
  the hour (12-hour clock) [1,12]; leading zeros are permitted but not required.
`%j`
  the day number of the year [1,366]; leading zeros are permitted but not required.
`%k`
  the same as `%H`.
`%l`
  the same as `%I`.
`%m`
  the month number [1,12]; leading zeros are permitted but not required.
`%M`
  the minute [0,59]; leading zeros are permitted but not required.
`%n`
  any whitespace.
`%p`
  the locale's equivalent of “AM” or “PM”.
`%r`
  the time as %I:%M:%S %p.
`%R`
  the time as %H:%M.
`%S`
  the seconds [0,60]; leading zeros are permitted but not required.
`%s`
  the number of seconds since the Epoch, UTC (see mktime(3)).
`%t`
  any whitespace.
`%T`
  the time as %H:%M:%S.
`%u`
  the day of the week as a decimal number, where Monday = 1.
`%U`
  the week number of the year (Sunday as the first day of the week) as a decimal number [0,53]; leading zeros are permitted but not required. All days in a year preceding the first Sunday are considered to be in week 0.
`%V`
  the ISO 8601 week number as a decimal number. If the week (starting on Monday) that contains January 1 has more than three days in the new year, then it is considered the first week of the year. If it has fewer than four days in the new year, then it is considered the last week of the previous year. Weeks are numbered from 1 to 53.
`%v`
  the date as %e-%b-%Y.
`%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 [0,53]; leading zeros are permitted but not required. All days in a year preceding the first Monday are considered to be in week 0.
`%x`
  the date, using the locale's date format.
`%X`
  the time, using the locale's time format.
`%y`
  the year within the current century. When a century is not otherwise specified, values in the range 69-99 refer to years in the twentieth century (1969 to 1999 inclusive); values in the range 00-68 refer to years in the twenty-first century (2000 to 2068 inclusive). Leading zeros are permitted but not required.
`%Y`
  the year, including the century (i.e., 1998).
`%z`
  an ISO 8601 or RFC 5322 timezone specification. This is one of the following: the offset from Coordinated Universal Time (‘`UTC`’) specified as: “[+-]hhmm”, “[+-]hh:mm”, or “[+-]hh”; ‘`UTC`’ specified as: “GMT” (‘`Greenwich Mean Time`’), “UT” (‘`Universal Time`’), or “Z” (‘`Zulu Time`’); a three character US timezone specified as: “EDT”, “EST”, “CDT”, “CST”, “MDT”, “MST”, “PDT”, or “PST”, with the first letter standing for ‘`Eastern`’ (“E”), ‘`Central`’ (“C”), ‘`Mountain`’ (“M”) or ‘`Pacific`’ (“P”), and the second letter standing for ‘`Daylight`’ (“D” or summer) time or ‘`Standard`’ (“S”) time.
`%Z`
  timezone name or no characters when timezone information is unavailable.
`%%`
  A `%' is read. No argument is converted.

The OpenBSD implementation always uses the C locale and ignores the global locale and the thread-specific locale. Alternative conversion modifiers have no effect.

There is no way to specify whether Daylight Saving Time is in effect when calling `strptime`. To use the resulting tm structure with functions that check the tm_isdst field, either set it to a negative value, which will cause mktime(3) to attempt to divine whether Daylight Saving Time would be in effect for the given time, or compute the value manually.

## Modified conversion specifications

For compatibility, certain conversion specifications 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 specification. As there are currently neither alternative formats nor specifications supported by the system, the behavior will be as if the unmodified conversion specification were used.

Case is ignored when matching string items in buf, such as month and weekday names.

# RETURN VALUES

If successful, the `strptime` function returns a pointer to the character following the last character parsed. Otherwise, a null pointer is returned.

# SEE ALSO

mktime(3), strftime(3)

# STANDARDS

The `strptime`() function conforms to the X/Open System Interfaces option of IEEE Std 1003.1-2008 (“POSIX.1”), except that flags and field width specifications are not supported.

The ‘`%F`’, ‘`%g`’, ‘`%G`’, ‘`%k`’, ‘`%l`’, ‘`%s`’, ‘`%u`’, ‘`%V`’, ‘`%z`’, and ‘`%Z`’ conversion specifications are extensions.

# CAVEATS

On systems other than OpenBSD, the `LC_TIME` locale(1) category can cause parsing failures; see CAVEATS in setlocale(3) for details.

# BUGS

The `%Z` format specifier only accepts timezone abbreviations of the local timezone, or the value “GMT”. This limitation is caused by the ambiguity of overloaded timezone abbreviations, for example EST is both Eastern Standard Time and Eastern Australia Summer Time.

August 26, 2025 | Debian