UNIX System time and User time. C-Programming

Question

Hi I'm trying to get the system time and the user time that are consumed by a program. I'm having some trouble though as my times are always zero in milliseconds. I think I'm doing something wrong. Can you guide me in the right direction ? Both of my methods return 0

typedef struct{
    struct timeval ru_utime; /* user time used */
    struct timeval ru_stime; /* system time used */
    long   ru_maxrss;        /* maximum resident set size */
    long   ru_ixrss;         /* integral shared memory size */
    long   ru_idrss;         /* integral unshared data size */
    long   ru_isrss;         /* integral unshared stack size */
    long   ru_minflt;        /* page reclaims */
    long   ru_majflt;        /* page faults */
    long   ru_nswap;         /* swaps */
    long   ru_inblock;       /* block input operations */
    long   ru_oublock;       /* block output operations */
    long   ru_msgsnd;        /* messages sent */
    long   ru_msgrcv;        /* messages received */
    long   ru_nsignals;      /* signals received */
    long   ru_nvcsw;         /* voluntary context switches */
    long   ru_nivcsw;        /* involuntary context switches */
}rusage;


/*************************************************************/


double getsystemtime(){
    struct timeval tim;
    struct rusage ru;
    getrusage(RUSAGE_SELF, &ru);
    tim = ru.ru_stime;
    double t = (double)tim.tv_sec / 1000.0;
    return t;
}

double getusertime(){
    struct timeval tim;
    struct rusage ru;
    getrusage(RUSAGE_SELF, &ru);
    tim = ru.ru_utime;
    double t = (double)tim.tv_sec / 1000.0;
    return t;
}

Answer 1

Shouldn't that be tim.tv_sec * 1000.0 + tim.tv_usec/1000.0 to convert to milliseconds? You're dividing tim.tv_sec by 1000 instead, so if your runtime is under 1000 sec, you'll get a return value of 0.

Answer 2

Yes, I agreed with Jim. Use the proper conversion otherwise you will get the return value zero.