Linux Compute program Run time

Turn from:

Http://www.cnblogs.com/NeilHappy/archive/2012/12/08/2808417.html


# include <sys/time.h>
int gettimeofday (struct timeval *tv,struct timezone *tz);
Strut Timeval {
Long tv_sec; /* Number of seconds */
Long tv_usec; /* microsecond number */
};
Gettimeofday Save the time in the structure TV. TZ generally we use NULL instead.

Here are the programs:
#i nclude <sys/time.h>
#i nclude <stdio.h>
#i nclude <math.h>
void function ()
{
unsigned int i,j;
Double y;
for (i=0;i<1000;i++)
for (j=0;j<1000;j++)
Y=sin (double) i);
}
Main ()
{
struct Timeval tpstart,tpend;
float Timeuse;
Gettimeofday (&tpstart,null);
function ();
Gettimeofday (&tpend,null);
timeuse=1000000* (TPEND.TV_SEC-TPSTART.TV_SEC) +
Tpend.tv_usec-tpstart.tv_usec; Note the millisecond and the subtle, the wrong output is zero.
timeuse/=1000000;
printf ("Used time:%f\n", timeuse);
Exit (0);
}

The result of this program running on my computer is probably 0.03-0.04s

Linux Compute program Run time