Difference between local time and UTC

[Generic Usenet Account]

I am trying to find the best way to get the difference between UTC and
the local time? Here's a small code snippet that I have written for
this purpose. Is there a better way to do this?

Thanks,
Bala

/*************************************************************************/
time_t getTimeOffset()
{
struct tm *gmTime;

time_t localEpoch, gmEpoch;

/*First get local epoch time*/
localEpoch = time(NULL);

/* Using local time epoch get the GM Time */
gmTime = gmtime(&localEpoch);

/* Convert gm time in to epoch format */
gmEpoch = mktime(gmTime);

/* get the absolute different between them */
return abs(gmEpoch - localEpoch);
}

 

[Eric Sosman]

Generic Usenet Account wrote On 05/22/06 15:42,:

I am trying to find the best way to get the difference between UTC and
the local time? Here's a small code snippet that I have written for
this purpose. Is there a better way to do this?

Thanks,
Bala

/*************************************************************************/
time_t getTimeOffset()
{
struct tm *gmTime;

time_t localEpoch, gmEpoch;

/*First get local epoch time*/
localEpoch = time(NULL);

/* Using local time epoch get the GM Time */
gmTime = gmtime(&localEpoch);

/* Convert gm time in to epoch format */
gmEpoch = mktime(gmTime);

/* get the absolute different between them */
return abs(gmEpoch - localEpoch);

Use difftime(gmEpoch, localEpoch) instead, and have
the function return a double. This makes things work
even on systems where time_t may be encoded in some other
way than a count of seconds elapsed since a Zero time.

Some error-checking would be a good idea, too. Yes,
there are systems that don't have calendar clocks, and
even among those that do there are some that simply run
their clocks in local time and have no notion of other
time zones.