The functionality described on this reference page is aligned with
the ISO C standard. Any conflict between the
requirements described here and the ISO C standard is unintentional.
This volume of IEEE Std 1003.1-2001 defers to
the ISO C standard.
The difftime() function shall compute the difference between
two calendar times (as returned by time()): time1- time0.
The difftime() function shall return the difference expressed
in seconds as a type double.
No errors are defined.
The following sections are informative.
asctime() , clock() , ctime()
, gmtime() , localtime() , mktime() , strftime()
, strptime() ,
time() , utime() , the Base Definitions volume of
IEEE Std 1003.1-2001, <time.h>
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at