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From: edw@ius2.cs.cmu.edu (Eddie Wyatt)
Newsgroups: comp.lang.c
Subject: Re: Types
Message-ID: <1173@ius2.cs.cmu.edu>
Date: Fri, 22-May-87 10:16:43 EDT
Article-I.D.: ius2.1173
Posted: Fri May 22 10:16:43 1987
Date-Received: Sat, 6-Jun-87 12:43:36 EDT
References: <7264@brl-adm.ARPA> <734@sdchema.sdchem.UUCP>, <293@osupyr.UUCP> <533@l.cc.purdue.edu>
Organization: Carnegie-Mellon University, CS/RI
Lines: 92

In article <533@l.cc.purdue.edu>, cik@l.cc.purdue.edu (Herman Rubin) writes:
> In article <8024@utzoo.UUCP>, henry@utzoo.UUCP (Henry Spencer) writes:
> > But this sure doesn't sound like C, and C is what X3J11 is standardizing.
> 
> Okay, let me stick to nasty problems with C.
> 
> 	1.  Have the compiler substitute locations in -asm- statements.
> 	Other than editing the assembler output, I do not believe there
> 	is any way to insert asm statements which can be expected to
> 	survive a change from one compiler to another.

	I have no idea what you are talking about.  The asm statement
	allows you to insert assemble code into your C program, what
	is the problem you are having with this?
> 
> 	2.  Require that the compiler honor, whenever possible, assignments
> 	to registers.				      ^^^^^^^^

	Is this really a problem?  Maybe I've been luckly, but when I ask
	for a register I get it provided I haven't used them all yet.
> 
> 	3.  Allow the programmer to force non-promotion of floating to double,
> 	whenever the programmer feels there is a good reason to do this.
> 	I know when there is no point in using double; the compiler cannot.
> 	Also, on some machines, one cannot print out a floating number in hex.
> 	(Okay, I can finagle it.  But I had an occasion where this would have
> 	been a problem.  I edited the assembler code, as the easiest option.)

	But heres the problem - floatfunc(3.0),  should 3.0 be pass as
	a float or a double?  To complicate matters, say floatfunc is
	external. Function prototypes may take care of this though.

	How about this to solve your problem.

		typedef union 
			{
			float fnum;
			int inum;
			} floatint;

		floatint num;

		num.fnum = 4.5;
		printf("%x\n",num.inum);

	which brings up - guess my bug:

		static void BBfwrite (val)
    		    float   val;
    		    {
    		    write_out_msg_buffer((char *) &val,sizeof(float));
    		    }

	The problem here  is fixed now.

> 
> 	4.  Allow floating point numbers to be given in hex.  Try putting in
> 	2^-32 as a floating point or double constant.  Why should one have to
> 	risk computer roundoff when it is totally unnecessary?

	Some people have noted that this might be a niece feature, I forget
	what if any problems there are with this.

> 
> 	5.  Require that the compiler honor parentheses.  When I want a   
> 	subroutine to return (x - y - k*c) + f(y), I most emphatically do
> 	not want the compiler to do the "obvious" rearrangement to combine
> 	the two terms with y; this can be a major loss of accuracy.  To set
> 	a variable equal to the parenthetical expression is a significant
> 	loss of time.

	What two terms with y?  I hope my C compiler doesn't think y can
	be factor out of that expression to form (f-1)(y) :-).
	To address your real complaint, the ANSI standard plans on supporting
	parenthesis honoring through the use of the unary +. +(x - y) + y
	will be evaluated as it appears.  If you don't like the unary
	+ put it into a define statement say:

		#define HONOR(x)	+(x)	

	Please lets not get into a long philosophic debate over this
	we have seen it all before.  If you don't like it, use another
	language.
> -- 
> Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907
> Phone: (317)494-6054
> hrubin@l.cc.purdue.edu or pur-ee!stat-l!cik or hrubin@purccvm.bitnet

-- 
					Eddie Wyatt

e-mail: edw@ius2.cs.cmu.edu