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From: ghoti+@andrew.cmu.edu (Adam Stoller)
Newsgroups: comp.lang.c
Subject: Re: Is there a good example of how toupper() works?
Message-ID: <sb75G4K00as9E8REZr@andrew.cmu.edu>
Date: 17 Oct 90 12:54:28 GMT
References: <2466@ux.acs.umn.edu> <15857@csli.Stanford.EDU>
	<1990Oct16.221035.10764@nntp-server.caltech.edu>
Organization: Information Technology Center, Carnegie Mellon, Pittsburgh, PA
Lines: 35
In-Reply-To: <1990Oct16.221035.10764@nntp-server.caltech.edu>

Both the original code posted and that as supplied by others - seems to
accept the fact that

	char *duh = "Hello";

can be modified.  From what I recall, for your simple test function to
work, you would either have to use:

	char duh[] = "Hello";

or pass/read in a string into either a malloc'ed area or char array --
before being able to modify it.

Of course I could be wrong - but...for my $0.02 function contribution:

#include <ctype.h>
int main()
{
    char duh[] = "Hello"; /* see (1), below */
    char *s = NULL;
    printf("%s\n", duh);
    for (s = duh; *s != '\0'; s++){
        *s = toupper(*s); /* see (2), below */
    }
    printf("%s\n", duh);
}

(1) some older compilers will require this to be declared static, before
allowing you to use aggregate initialization.

(2) under ANSI you don't need to test for islower() - pre-ANSI requires
the islower() test because many of the macros used to define islower and
toupper were brain-dead

--fish