Re: Platform-dependent variations in numeric conversions

[Asko Kauppi <askok@...>]

I believe LNUM patch at least tries to make hexadecimal input uniform  
across platforms.  In other words, it makes it work even if the  
system's 'strtod()' did not support hex.

-asko


Duck kirjoitti 16.6.2008 kello 1:06:

> Under Linux (gcc 4.x and associated libraries)
>
> Lua 5.1.3  Copyright (C) 1994-2008 Lua.org, PUC-Rio
> % = 0x12345678
> 305419896
> % = -0x12345678
> -305419896
> % = tonumber(-0x12345678)
> -305419896
> % return  tonumber('-0x12345678')
> -305419896
> >
>
> Under Windows (MinGW 3.x and associated libraries)
>
> Lua 5.1.3  Copyright (C) 1994-2008 Lua.org, PUC-Rio
> > = 0x12345678
> 305419896
> > - 0x12345678
> stdin:1: unexpected symbol near '-'
> > = -0x12345678
> -305419896
> > = tonumber(-0x12345678)
> -305419896
> > return  tonumber('-0x12345678')
> 39895547400
> >
>
> The Windows string conversion seems to be "unsigned 32-ing" the  
> converted
> number, whereas the Linux one is not. I presume the compiler does the
> negation of hex constants itself, therefore producing consistent  
> results.
>
> I think it can be considered a bug that (de)hexadecimalisation isn't  
> coded
> inside Lua itself, making hex and decimal numbers equal-class lexical
> citizens on all platforms instead of relying on runtime library  
> vagaries.
>
> Is there some luaconf.h finessing I can do to make good under MinGW on
> Windows? .