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From: tim@nucleus.amd.com (Tim Olson)
Newsgroups: comp.os.minix
Subject: Re: float VS double: The return...
Message-ID: <29812@amdcad.AMD.COM>
Date: 10 Apr 90 18:10:35 GMT
References: <16383@nigel.udel.EDU>
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Reply-To: tim@amd.com (Tim Olson)
Organization: Advanced Micro Devices, Inc., Austin, Texas
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In article <16383@nigel.udel.EDU> ARCHER@segin4.segin.fr writes:
| I don't think for my compiler :-), but a compiles as a double (sizeof being 8),
| and *a in test1 has nothing near the same value as a in test:
| 
|     test(a) float a;
|     {
|     a = 0.1;
|     printf("%f\n", a);
|     test1(&a);
|     }
| 
|     test1(a) float *a;
|     {
|     printf("%f\n", *a;
|     }
| 
| said:
| 
| 0.1
| 1.45000
| 
| 
| It seems that most compilers do the same kind of thing. So if your compiler
| enables the user to do some mistakes, you'll lose portability: The program will
| work compiled with C68, and not with any other compiler. What's more important?

If you want to start progressing towards ANSI compatibility, then this
must be fixed.  The Standard says (in the Rationale Section):

	Some current implementations rewrite the type of a (for
	instance) |char| parameter as if it were declared |int|, since
	the argument is known to be passed as an |int| (in the absence
	of prototypes).  The Standard requires, however, that the
	received argument be converted "as if" by assignment upon
	function entry.  Type rewriting is thus no longer permissible.


This means that in:

f(c, f)
char c;
float f;
{
	.
	.
sizeof c should be 1 and sizeof f should be equal to sizeof(float).

	-- Tim Olson
	Advanced Micro Devices
	(tim@amd.com)