OFFTIME(3) BSD Library Functions Manual OFFTIME(3)
offtime, timeoff, timegm, timelocal -- convert date and time
Standard C Library (libc, -lc)
struct tm *
offtime(const time_t * clock, long int offset);
struct tm *
offtime_r(const time_t * clock, long int offset, struct tm *ret);
timeoff(struct tm * tm, long int offset);
timegm(struct tm * tm);
timelocal(struct tm * tm);
These functions are inspired by C standard interfaces named similarly.
offtime() converts the calendar time clock, offset by offset seconds, into broken-down time, expressed as Coordinated Universal Time (UTC).
offtime_r() is similar to offtime() but it places the returned struct tm * in the user supplied ret argument.
timeoff() converts the broken-down time tm, expressed as UTC, offset by offset seconds, into a calendar time value.
timegm() converts the broken-down time tm into a calendar time value, effectively being the inverse of gmtime(3). It is equivalent to the C
standard function mktime(3) operating in UTC.
timelocal() converts the broken down time tm, expressed as local time, into a calendar time value. It is equivalent to the C standard func-
tion mktime(3), and is provided for symmetry only.
ctime(3), tm(3), tzset(3)
April 14, 2011 BSD