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From: "Rupert Wood" <me@rupey.net>
To: "'Grant Gossett'" <ggossett@symantec.com>
Cc: <gcc-help@gcc.gnu.org>,
	<shamus@tdcadsl.dk>
Subject: RE: statements following strcpy cause parse error
Date: Fri, 08 Feb 2002 01:28:00 -0000
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Bjorn Rohde Jensen wrote:

> > prog # 2 which throws a parse error before 'char'  (meaning 
> > the strcpy
> > line??)
> > 
> > #include <string.h>
> > int main()
> > {
> >      char filename[256];
> >      strcpy (filename, "/etc/bogus.conf\0");
> >      char unused[256];
> >      return 0;
> > }
>
>  In prog#2 you declare a variable in the function body, that is a C++
> feature, so prog#2 is legal C++ but illegal C. You have to move the
> declaration to the top of main to make it legal C.

Yes; alternately, you can introduce a new scope for the new variable:

    #include <string.h>
    int main()
    {
         char filename[256];
         strcpy (filename, "/etc/bogus.conf\0");

         {
             char unused[256];
         }

         return 0;
    }

because you are also allowed to introduce new variables at the top of
new scopes (which applies equally to if/for/while scopes, etc.). I've
heard apocryphal stories about compilers mis-optimising this
construction - but you're safe with GCC :-)

You also don't need the \0 at the end of the string unless you
deliberaltely want two - you automatically get nuls at the end of string
constants. (And as a strcpy source, you *don't* need two.) Further style
- you may want to use strncpy instead:

         char filename[256];
         strncpy (filename, "/etc/bogus.conf\0", 256);

or maybe

         strncpy (filename, "/etc/bogus.conf\0", sizeof(filename));

just to get into the habit of using it if nothing else; this helps
prevent buffer-overflow security holes.

(You may even want avoid assuming that characters are size 1

         strncpy (filename, "/etc/bogus.conf\0",
                  sizeof(filename)/sizeof(filename[0]));

for unicode, etc. - but then you'd need to change function and
string-constant style, etc.)

Rup.