Hello Terrence,
I do not think it is possible to set an environment variable to an empty
string on Windows. This amounts to undefining it.
I have found the same problem with setenv() and unsetenv() on my
venerable platform (Windows XP, 32 bits, with MSVC 6.0). I will create
a workaround using putenv(), because right now building PLplot stops
on the QSAS test program.
Regards,
Arjen
On 2009-02-14 17:05, trc wrote:
> Hi Alan,
>
> Alan W. Irwin wrote:
>>> [out of order] 4. qsastime_testlib cannot be built with MSVC 2008 as
>>> setenv and unsetenv
>>> are not implemented.
>>>
>>> [so] the above changes
>>> are untested.
>> Is this a showstopper for MSVC 2008 or do you think you can find for that
>> platform (a) some library alternatives for setenv and unsetenv, (b) some
>> other alternative to set the time zone to zero temporarily which would make
>> mktime act like an inverse to gmtime, or (c) some other alternative that is
>> equivalent to the Linux timegm or the inverse of gmtime?
>>
>
>
> There are too many problems to make qsastime_testlib worthwhile on 32 bit
> Windows XP with MSVC 2008 (and earlier editions) even with 64 bit time_t
> values.
>
> 32 bit Windows XP / MSVC 2008 has extensions for 64 bit time_t values and a
> function _mkgmtime64 for converting times a struct tm to 64 bit time_t.
> Unfortunately mkgmtime64 returns -1 for all times prior to 1/1/1970.
>
> A further problem for qsastime_testlib is that the MSVC debug version of
> strftime throws an exception for years less than 0 or greater than 9999.
>
> For the record MSVC has the (unix) putenv function which can be used to
> implement setenv and unsetenv. However googling putenv suggests there could
> be problems with memory leaks and care has to be taken over
> ownership/lifetime of the environment variables. Further it is unclear how an
> environment variable is set to empty string. eg.
> setenv("TZ","",1) -> putenv("TZ=")
> This unsets TZ rather than setting it to an empty string.
>
>
> Default 32 bit Cygwin compiles and links but has 32 bit time_t so testing is
> not done. I didn't investigate if there were 64bit time_t extensions.
>
> Note my investigations were on a 32bit Windows XP system so this excludes 32
> bit Vista and 64bit versions of XP and Vista.
>
>
> Terrence
>
>
>
>
>
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