• NAME
  
  difftime - calculate time difference
• SYNOPSIS
  

  
   #include <time.h>
  
   double difftime(time_t  time1 , time_t  time0 );
  

• DESCRIPTION
  
  The
  difftime ()
  function returns the number of seconds elapsed
  between time time1 and time time0, represented as a
  double .
  The two times are specified in calendar time, which represents the time
  elapsed since the Epoch
  (00:00:00 on January 1, 1970, Coordinated Universal Time (UTC)).
  
• CONFORMING TO
  
  SVr4, 4.3BSD, C89, C99.
  
• NOTES
  
  On a POSIX system,
  time_t
  is an arithmetic type, and one could just
  define
  

  
  
  #define difftime(t1,t0) (double)(t1 - t0)
  
  

  when the possible overflow in the subtraction is not a concern. On other systems, the data type time_t might use some other encoding where subtraction doesn't work directly.
• SEE ALSO
  
  date(1) , gettimeofday(2) , time(2) , ctime(3) , gmtime(3) , localtime(3)
• COLOPHON
  
  This page is part of release 3.19 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.

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