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From: gnu@hoptoad.uucp (John Gilmore)
Newsgroups: net.lang.c
Subject: Help me out on Float Double Parameters
Message-ID: <667@hoptoad.uucp>
Date: Wed, 9-Apr-86 04:53:07 EST
Article-I.D.: hoptoad.667
Posted: Wed Apr  9 04:53:07 1986
Date-Received: Fri, 11-Apr-86 00:47:49 EST
References: <2600042@ccvaxa> <5216@alice.uUCp> <2442@utcsri.UUCP> <3439@sun.uucp>
Organization: Nebula Consultants in San Francisco
Lines: 49

In article <3439@sun.uucp>, guy@sun.uucp (Guy Harris) writes:
> Mr. Koenig is correct.  According to the August 11, 1985, X3J11 draft:
> 
> 	C3.2.2 Function calls
> 
> 	... Also, *if no function prototype declarator is in scope*, the
> 	integral promotions are performed and arguments that have type
> 	"float" are promoted to "double".  ("italics" mine)
> 
> 	... If a function prototype declarator is in scope, the arguments
> 	are compared with the formal parameters.  ...The types must be
> 	such that each formal parameter may be initialized by the
> 	coresponding argument, and the arguments are converted
> 	accordingly.

I think the above applies to CALLS of the function, not DEFINITIONS of the
function.  But let me see if I understand how this works.  If I write:

	foo(float x) {...}		/* DEFINE */

then (if this is legal, which I don't know) it expects it as float.
(Of course, any time the DEFINITION expects float, there had better
be a DECLARATION in the callers' routines that matches.)

	foo(x)  float x;  {...}		/* DEFINE */

I presume for compatability it must expect double.

	foo(float x);			/* DECLARE */

	foo(x)  float x;  {...}		/* DEFINE */

Now maybe it can expect float?  Suppose the declaration and the
definition are separated by a few pages, or the declaration is in
a header file -- how will you know what the routine expects?

	foo(float x)  float x;  {...}	/* DEFINE */

Is this legal?  Does it take float or double?

Is the same true if you declare an argument char or short?  Does it
avoid the widening to int on the stack?

I can see that no matter what the answers to the above questions, the C
standardization process is not making C any simpler to use.  Sigh.
Feeping creatureism is leaving its trail of turds.
-- 
John Gilmore  {sun,ptsfa,lll-crg,ihnp4}!hoptoad!gnu   jgilmore@lll-crg.arpa
			     Post no bills.