mktime

Syntax

#include <time.h> time_t mktime(struct tm *tptr);

Description

This function converts a time structure into the number of seconds since 00:00:00 GMT 1/1/1970. It also attempts to normalize the fields of tptr. The layout of a struct tm is as follows:

struct tm { int tm_sec; /* seconds after the minute [0-60] */ int tm_min; /* minutes after the hour [0-59] */ int tm_hour; /* hours since midnight [0-23] */ int tm_mday; /* day of the month [1-31] */ int tm_mon; /* months since January [0-11] */ int tm_year; /* years since 1900 */ int tm_wday; /* days since Sunday [0-6] */ int tm_yday; /* days since January 1 [0-365] */ int tm_isdst; /* Daylight Savings Time flag */ long tm_gmtoff; /* offset from GMT in seconds */ char * tm_zone; /* timezone abbreviation */ };

If you don't know whether daylight saving is in effect at the moment specified by the contents of tptr, set the tm_isdst member to -1, which will cause mktime to compute the DST flag using the data base in the `zoneinfo' subdirectory of your main DJGPP installation. This requires that you set the environment variable TZ to a file in that directory which corresponds to your geographical area.

Return Value

The resulting time, or -1 if the time in tptr cannot be described in that format.

Portability

ANSI/ISO C	C89; C99
POSIX	1003.2-1992; 1003.1-2001