Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!jarthur!nntp-server.caltech.edu!bruce
From: bruce@seismo.gps.caltech.edu (Bruce Worden)
Newsgroups: comp.lang.c
Subject: char *'s and const char *'s (followup)
Message-ID: <1991Jan16.234202.20933@nntp-server.caltech.edu>
Date: 16 Jan 91 23:42:02 GMT
References: <1991Jan11.182945.5437@nntp-server.caltech.edu> <14825@smoke.brl.mil>
Sender: bruce@seismo.gps.caltech.edu (Bruce Worden)
Organization: California Institute of Technology, Pasadena
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Nntp-Posting-Host: sis.gps.caltech.edu


Thanks to everyone who responded here and by e-mail.  I got a number of
interesting responses.  Doug's was typical:

In article <14825@smoke.brl.mil> gwyn@smoke.brl.mil (Doug Gwyn) writes:
>In article <1991Jan11.182945.5437@nntp-server.caltech.edu> bruce@seismo.gps.caltech.edu (Bruce Worden) writes:
>>Given:
>>int foo(char *file);
>>And knowing that foo() really only needs a const char *, it is often called as:
>>	a = foo("myfile");
>>but a kindly compiler will warn something like:
>>	junk.c:7: warning: argument passing of non-const * pointer from const *
>
>You should have declared foo as int foo(const char *file).  No diagnostic
>should be generated when a pointer to non-const char is passed as an
>argument to the function, and of course no diagnostic would be issued
>for a pointer to const char either.

Which is, of course, the correct approach.  However, when I wrote "Given:" 
I really meant "Given:".  So based on the comments I got, I can nag the 
supplier of the code, a task which I will gleefully undertake.  In the 
meantime I will use:

	char descriptive_name[] = "myfile";

	...
	a = foo(descriptive_name);
	...

As a number of people suggested.  Thanks again.
--------------------------------------------------------------------------
C. Bruce Worden                            bruce@seismo.gps.caltech.edu
252-21 Seismological Laboratory, Caltech, Pasadena, CA 91125