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From: jerry@ucbopal.berkeley.edu (Jerry Berkman)
Newsgroups: net.lang
Subject: Re:   [Really: C builtin functions?]
Message-ID: <563@jade.BERKELEY.EDU>
Date: Tue, 15-Apr-86 20:59:40 EST
Article-I.D.: jade.563
Posted: Tue Apr 15 20:59:40 1986
Date-Received: Fri, 18-Apr-86 05:37:35 EST
Sender: usenet@jade.BERKELEY.EDU
Reply-To: jerry@ucbopal.UUCP (Jerry Berkman)
Organization: University of California, Berkeley
Lines: 37
Keywords: C

>In article <149@diablo.ARPA> avg@diablo.UUCP (Allen VanGelder) writes:
>>I think there may be a confusion in terminology between built-in and
>>in-line.  In FORTRAN, MAX is expanded in-line, so you always get
>>FORTRAN's MAX.  But SIN is not, and if you jiggle your libraries
>>properly you will get your personal SIN function.  The same is true
>>for READ and WRITE in FORTRAN.
>>
>>I still call SIN, READ, and WRITE built-in in any language where the
>>language manual tells how to use them and what they do.

Not true.  Try this program on with a 1977 standard compiler:

	print *, sin(1.0)
	end
	function sin(x)
	sin = 2.0
	end

When I compile it and run it on 4.3 BSD UNIX, I get:
  0.841471
sin() is an intrinsic listed in the standard, and you get it
even if there is a Fortran function you wrote with a similar name.
If you want your own function instead, you must say:

	external sin

and then sin() is no longer treated as an intrinsic in that program
unit.  If you write in assembler or C, you can create names to
fake out the Fortran standard, but not if you stay within Fortran.
By contrast, if you see sin(), or strcmp() or printf() in a C program,
there is no way of telling if that is refering to the commonly
referenced library routine or the program's author's own personal function.

	- Jerry Berkman
	  Academic Computing Services
	  U. C. Berkeley (415) 642-4804
	  jerry@ucbopal.Berkeley.EDU