Mail Archives: cygwin/2005/10/20/09:45:25
Hi,
I'm sorry. After your answer i realised that my
message should be posted on a c/c++ mailing list not
in this one.
Sorry again
--- Eric Blake <ebb9 AT byu DOT net> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> According to community help on 10/20/2005 7:06 AM:
> > Hi,
> >
> > I'm using g++ on cygwin for developping some c++
> > programs.
> >
> > I noticed that everytime i manipulate pointers i
> have
> > an error saying:
> > "Segmentation Fault <Core Dumped>".
>
> Well, it's because you are trying to modify
> read-only memory. Fix the bug
> in your code. Your problem is not cygwin-specific,
> although cygwin is a
> little less forgiving of memory usage errors, and
> more likely to core dump
> when your code is buggy.
>
> > ----------------------
> > #include <iostream.h>
> > #include <string.h>
> >
> > int main()
> > {
> > char * str;
> > str = "hello";
>
> The type of "hello" is const char*, because it lives
> in read-only memory.
> You are (silently) casting away the const, and that
> is your bug; compile
> with -Wall and you should be getting a warning.
>
> > *(str+1) = 'a';
>
> Oops - now you are trying to change a read-only
> location.
>
> Now, had you declared this instead:
> char str[] = "hello";
>
> Then *(str+1) = 'a' is legal, because C++ allows a
> char[] initializer to
> copy the contents of a string literal, without
> putting it in read-only memory.
>
> - --
> Life is short - so eat dessert first!
>
> Eric Blake ebb9 AT byu DOT net
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.1 (Cygwin)
> Comment: Public key at
> home.comcast.net/~ericblake/eblake.gpg
> Comment: Using GnuPG with Thunderbird -
> http://enigmail.mozdev.org
>
>
iD8DBQFDV5vv84KuGfSFAYARAg+yAJwIbqTkFDH5j9+a3Mmn2ON7KL8rwgCfTALA
> v2bKNT8djHRvcVBHSSuFQ7g=
> =/+gu
> -----END PGP SIGNATURE-----
>
> --
> Unsubscribe info:
> http://cygwin.com/ml/#unsubscribe-simple
> Problem reports:
> http://cygwin.com/problems.html
> Documentation: http://cygwin.com/docs.html
> FAQ: http://cygwin.com/faq/
>
>
__________________________________
Yahoo! Music Unlimited
Access over 1 million songs. Try it free.
http://music.yahoo.com/unlimited/
--
Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
Problem reports: http://cygwin.com/problems.html
Documentation: http://cygwin.com/docs.html
FAQ: http://cygwin.com/faq/
- Raw text -