mktime() failure vs 31-DEC-1969 23:59:59 GMT
Arthur David Olson
Wed Feb 14 18:00:02 UTC 1996
> > The standards for mktime() define a return value of
> > (time_t)-1 as indicating that the time specified cannot be
> > represented. However, a return value of -1 is also a valid time_t
> > corresponding to 31-DEC-1969 23:59:59 GMT. How do we distinguish
> > between the two?
> Call localtime() on the seemingly-in-error mktime() result, and compare
> the relevant portions of the structs tm. A match implies a non-error.
Since there's normalization going on in mktime, the tm that comes back from
localtime may not match the one that went in to mktime even if -1 is being
returned as a legitimate time_t rather than an error indication.
Another possibility is to save away the original tm structure; if mktime
returns -1, bump the tm_sec value by 1, call mktime again, and see if it
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