Standard C Digest - V2 #1

[Orlando Sotomayor-Diaz]

ANSI Draft of Proposed  C Language Std.

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**************** mod.std.c  Vol. 2 No. 1  1/4/85 ********************

Today's Topics:

		Scientific notation (2)
		Union initialization (1)
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Date: Tue, 18 Dec 84 06:40:07 est
From: Robert Scott Lenoil <cbosgd!ihnp4!mit-eddie!lenoil>
To: ihnp4!seismo!elsie!ado
Subject: scientific notation

> *	In section B.3.4.1 (page 10) appears:
> 
> 		* maximum exponent power of ten that floating point can
> 		  represent	38
> 
> 	On our 4.1bsd system, the program:
> 		main() { printf("%f\n", 10.0e37);printf("%f\n", 10.0e38); }
> 	produces this output:
> 		100000000000000000000000000000000000000.000000
> 		170141183460469230000000000000000000000.000000
> 	which means (to me) that 37 is the maximum "power of ten" that floating
> 	point can represent.  Either I or the description can stand being made
> 	clearer.


You could stand to be made clearer.  10.0e38 means 10.0 x 10^38, i.e. 10^39.
If you used 1.0e38 your program would have worked.

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Date: Tue, 18 Dec 84 08:44:26 EST
From: cbosgd!seismo!elsie!ado
To: mit-eddie!lenoil
Subject: Re: scientific notation

Thanks for the correction.  Mea culpa.

				--ado

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Date: Fri 4 Jan 85 10:22:02-PST
From: Joseph I. Pallas <cbosgd!ucbvax!PALLAS at SU-SCORE.ARPA>
Subject: Standard for union initialization?

Perhaps I'm out of touch.... An article I read about the draft
standard said the standard would allow initialization of unions, but
the first union field would be the type used for the initialization.

Instead of insisting on

	union {
	    <type1> foo;
	    <type2> bar;
	    <type3> mumble;
	} baz = <type1 initializer>;

why not use a more general scheme like

	union {
	    <type1> foo;
	    <type2> bar;
	    <type3> mumble;
	} baz.mumble = <type3 initializer>;

Since no existing compiler that I know of lets you initialize unions
at all currently, there's nothing to be lost by going with the more
flexible system.

joe

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End of Vol. 2, No. 1. Std-C  (Jan. 4, 1985  21:40:00)
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Orlando Sotomayor-Diaz/AT&T Bell Laboratories/201-870-7249
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