The Single UNIX ® Specification, Version 2
Copyright © 1997 The Open Group


localtime, localtime_r - convert a time value to a broken-down local time


#include <time.h>

struct tm *localtime(const time_t *timer);
struct tm *localtime_r(const time_t *clock, struct tm *result);


The localtime() function converts the time in seconds since the Epoch pointed to by timer into a broken-down time, expressed as a local time. The function corrects for the timezone and any seasonal time adjustments. Local timezone information is used as though localtime() calls tzset().

The localtime() interface need not be reentrant.

The localtime_r() function converts the calendar time pointed to by clock into a broken-down time stored in the structure to which result points. The localtime_r() function also returns a pointer to that same structure.

Unlike localtime(), the reentrant version is not required to set tzname.


The localtime() function returns a pointer to the broken-down time structure.

Upon successful completion, localtime_r() returns a pointer to the structure pointed to by the argument result.


No errors are defined.




The asctime(), ctime(), getdate(), gettimeofday(), gmtime() and localtime() functions return values in one of two static objects: a broken-down time structure and an array of char. Execution of any of the functions may overwrite the information returned in either of these objects by any of the other functions.




asctime(), clock(), ctime(), difftime(), getdate(), gettimeofday(), gmtime(), mktime(), strftime(), strptime(), time(), utime(), <time.h>.


localtime() derived from Issue 1 of the SVID.

localtime_r() derived from the POSIX Threads Extension (1003.1c-1995).

UNIX ® is a registered Trademark of The Open Group.
Copyright © 1997 The Open Group
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