How get the time in milliseconds in FreeBSD?

The BSD date command doesn't support milliseconds. If you want a date with millisecond support, install the GNU coreutils package.

I encountered this on OS X, whose date comes from BSD. The solution was to brew install coreutils and ln -sf /usr/local/bin/gdate $HOME/bin, and making sure that $HOME/bin comes first in PATH.

Use gettimeofday(), for example:

#include <stdio.h>
#include <sys/time.h>
int main(void)
{
  struct timeval time_now;
    gettimeofday(&time_now,NULL);
    printf ("%ld secs, %ld usecs\n",time_now.tv_sec,time_now.tv_usec);

    return 0;
}