Subj : Re: Any help on why?
To   : borland.public.cpp.borlandcpp
From : waking
Date : Thu Jul 08 2004 07:29 am

On Wed, 07 Jul 2004 13:45:43 -0700, Bob Gonder <notbg@notmindspring.invalid>
wrote:

>>In fortran I can map an array of integers on top of an array of
>>floating point.
>>Is there a similar operation within C ?
>
>See union.

But be forewarned (from the BC++ 5.02 and Builder help):
=================================================
3.1.2.5 The representations and sets of values of the various types of
floating-point numbers.

The IEEE floating-point formats as used by the Intel 8087 are used for
all Borland C++ floating-point types. The float type uses 32-bit IEEE
real format. The double type uses 64-bit IEEE real format. The long
double type uses 80-bit IEEE extended real format.

[snip]

3.3.2.3 What happens when a member of a union object is accessed using a
member of a different type.

The access is allowed and the different type member will access the bits
stored there. You’ll need a detailed understanding of the bit encodings
of floating-point values to understand how to access a floating-type
member using a different member. If the member stored is shorter than
the member used to access the value, the excess bits have the value they
had before the short member was stored.
=============================================================

>printf( "%LI", number.i );

Upper case "I"?

If so inclined, you might also experiment with:
printf("%I64d", number.i);
printf("%I64X", number.i);
and:
char *_i64toa(__int64 value, char *strP, int radix);
char *_ui64toa(unsigned __int64 value, char *strP, int radix);
using a radix of 16 (and also radix 2).

Of the BC++ line, only 5.02 supports these for 32-bit targets.
None of the above can be used with any 16-bit compiler.
None of the above are ANSI-compliant. (Haven't checked C99.)


--
Wayne A. King 
(waking@idirect.com, Wayne_A_King@compuserve.com)

.