Big hex numbers negative?

[Bill Medland]

On February 23, 2004 08:41 am, Shachar Shemesh wrote:
> Fabian Cenedese wrote:
> >Hi
> >
> >While testing more variant functions I tried this on Windows:
> >
> >double dVal;
> >OLECHAR test1[]={'&', 'H', '8', '0', '0', '0', '0', '0', '0', '0', '\0'};
> >ok=VarR8FromStr(test1, LANG_NEUTRAL, NUMPRS_STD, &dVal);
> >
> >The result for dVal was -2147483648. But as a real value it shouldn't
> >have any problems holding the "real" value 2147483648. So why has
> >it become negative? Is it because the source form was a hex number?
> >Are all hex numbers automatically signed if converted to int/real? Or
> >just because of the 32nd bit? The documentation wasn't that informative.
> >
> >(The funny thing though was this remark in my VC6 help, it's not
> >in the online version of MSDN anymore:
> >Passing into this function any invalid and, under some circumstances, NULL
> > pointers will result in unexpected termination of the application. For
> > more information about handling exceptions, see Programming
> > Considerations.
> >
> >...now I understand many things :)
Now does that mean "invalid numbers" or "invalid pointers"?  Are they just 
saying that they hadn't included IsBadReadPtr in the argument checking?
> >
> >Thanks
> >
> >bye   Fabi
>
> I'm not sure I understood your question properly.
> A signed 2 complement 32 bit var can hold the numbers (-2^31) to
> (2^31)-1. That's just how the encoding works. Was that your question?
>
>              Shachar
Because there is nothing explicitly in there about 32 bit representations.  It 
goes from a string of characters to a (excuse my ignorance) 64 bit double 
prescision.  So are there restrictions on what character strings can be 
passed in?  e.g. what would it do with "&H80000000"?

-- 
Bill Medland
mailto:billmedland at mercuryspeed.com
http://webhome.idirect.com/~kbmed