STRPTIME

strptime ? convert a string representation of time to a time tm structure

#include <time.h>

char *strptime(const char *s, const char *format, struct tm *tm);

strptime() is the complementary function to strftime() and converts the character string pointed to by s to a time value, which is stored in the tm structure pointed to by tm, using the format specified by format. format is a character string that consists of field descriptors and text characters, reminiscent of scanf(3). Each field descriptor consists of a % character followed by another character that specifies the replacement for the field descriptor. All other characters in the format string must have a matching character in the input string. Exceptions are white spaces in the format string which can match zero or more white space characters in the input string.

The strptime() function processes the input string from right to left. Each of the three possible input elements (white space, literal, or format) are handled one after the other. If the input cannot be matched to the format string the function stops. The remainder of the format and input strings are not processed.

The following field descriptors are supported:

%%

same as %

%a

%A

day of week, using locale’s weekday names; either the abbreviated or full name may be specified

%b

%B

%h

month, using locale’s month names; either the abbreviated or full name may be specified

%c

date and time as %x %X

%C

date and time, in locale’s long-format date and time representation

%d

%e

day of month (1-31; leading zeroes are permitted but not required)

%D

date as %m/%d/%y

%H

%k

hour (0-23; leading zeroes are permitted but not required)

%I

%l

hour (0-12; leading zeroes are permitted but not required)

%j

day number of year (001-366)

%m

month number (1-12; leading zeroes are permitted but not required)

%M

minute (0-59; leading zeroes are permitted but not required)

%p

locale’s equivalent of AM or PM

%r

time as %I:%M:%S %p

%R

time as %H:%M

%S

seconds (0-61; leading zeroes are permitted but not required. Extra second allowed for leap years)

%T

time as %H:%M:%S

%w

weekday number (0-6) with Sunday as the first day of the week

%x

date, using locale’s date format

%X

time, using locale’s time format

%y

year within century (0-99; leading zeroes are permitted but not required. Unfortunately this makes the assumption that we are stuck in the 20th century as 1900 is automatically added onto this number for the tm_year field)

%Y

year, including century (for example, 1988)

Case is ignored when matching items such as month or weekday names.

The broken-down time structure tm is defined in <time.h> as follows:

struct tm
{

int

tm_sec;

/* seconds */

int

tm_min;

/* minutes */

int

tm_hour;

/* hours */

int

tm_mday;

/* day of the month */

int

tm_mon;

/* month */

int

tm_year;

/* year */

int

tm_wday;

/* day of the week */

int

tm_yday;

/* day in the year */

int

tm_isdst;

/* daylight saving time */

};

The return value of the function is a pointer to the first character not processed in this function call. In case the input string contains more characters than required by the format string the return value points right after the last consumed input character. In case the whole input string is consumed the return value points to the NUL byte at the end of the string. If strptime() fails to match all of the format string and therefore an error occurred the function returns NULL.

strftime(3), time(2), setlocale(3), scanf(3)

The specification of the function in the XPG standard is rather vague. It leaves out a few important pieces of information. Most important it does not specify what happens to those elements of tm which are not directly initialized by the different formats. Various implementations on different Unix systems vary here.

The GNU libc implementation does not touch those fields which are not directly initialized. Exceptions are the tm_wday and tm_yday elements which are recomputed if any of the year, month, or date elements changed.

This function is only available in libraries newer than version 4.6.5. Linux libc4 and libc5 includes define the prototype unconditionally; glibc2 includes provide a prototype only when _XOPEN_SOURCE or _GNU_SOURCE are defined.

The function supports only those locales specified in locale(7)