[Jscheme-user] Fwd: Re: Converting octal and hex strings to numbers in java.

[Ken A. <kan...@bb...>]

This is a reply i got from Guy Steele about a bug Jonathan Reese reported, and the problems i ran into trying to fix it.

I'm planning to rewrite our number reader one day and include the mail as a comment, but i thought it worth passing to the group because it may take me a while to get around to it.  Though it might not be worth being more consistent about numbers than Java is, so maybe the current behavior is good enough.

>Date: Wed, 8 Jan 2003 14:03:48 -0500 (EST)
>From: Guy Steele - Sun Microsystems Labs <Guy...@su...>
>Reply-To: Guy Steele - Sun Microsystems Labs <Guy...@su...>
>Subject: Re: Converting octal and hex strings to numbers in java.
>To: Guy...@su..., kan...@bb...
>
>
>
>   X-Sender: kan...@zi...
>   Date: Mon, 30 Dec 2002 15:46:39 -0500
>   To: Guy Steele - Sun Microsystems Labs <Guy...@su...>
>   From: Ken Anderson <kan...@bb...>
>   Subject: Converting octal and hex strings to numbers in java.
>   
>   I hope you can answer this question easily.
>   
>   I was tracking down a problem the Jonathan Reese found in JScheme which will 
>optionally read numbers in either Java or Scheme format.
>   
>   Reading the JVS spec, 
>http://java.sun.com/docs/books/jls/second_edition/html/lexical.doc.html#230798
>   
>   it says numbers like 0xDadaCafe are valid integer constants.  however, 
>   Integer.parseInt("DadaCafe", 16) throws a NumberFormatException, as the 
>enclosed program shows.  I think Long.parseLong() has a similar problem.
>   I presume this has to do with the sign of the number.  Can you shed some 
>light on this?  Is there something else i can use to read such number?
>
>Unfortunately, the detailed description of Integer.ParseInt that
>appeared in JLS1 was not carried forward into JLS2, nor was it
>transferred to "The Java Class Libraries".  That description
>makes clear that "overly large" hexadecimal numbers are not
>accepted by ParseInt, even though literals of that form are
>indeed accepted by the compiler.
>
>That may be regarded as a flat-out inconsistency in the language,
>but that's just the way it is, I'm afraid.  ParseInt is not the
>right tool for parsing hexadecimal integer literals.  You may have
>to roll yur own.  Sorry about that.
>
>--Guy