Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.arch.embedded > #27997
| From | David Brown <david.brown@hesbynett.no> |
|---|---|
| Newsgroups | comp.arch.embedded |
| Subject | Re: arm-gcc: pointer to constant string |
| Date | 2018-09-14 11:18 +0200 |
| Organization | A noiseless patient Spider |
| Message-ID | <pnfudg$7p2$1@dont-email.me> (permalink) |
| References | <pnfp7q$a7b$1@dont-email.me> |
On 14/09/18 09:50, pozz wrote:
> --- 1.c ---
> void foo(void) {
> dummy("hello");
> }
>
> --- 2.c ---
> static const char *s;
>
> void dummy(const char *ss) {
> s = ss;
> }
>
>
>
> "hello" is a constant string declared inside function foo(). Is there a
> guarantee that his pointer (passed to dummy()) is valid after exiting
> foo()? In other words, is the string on the stack (in this case it will
> not be valid after foo()) or in Flash (so it is permanent)?
It is not guaranteed by C, AFAIUI - the literal is only valid during
its lifetime, which ends when the call to "dummy" returns. However, gcc
always places such strings in flash and it will remain valid throughout
the program's lifetime. I cannot see that changing in any future
version of gcc.
But note that the same does not apply to pointers to other objects that
might reasonably be put on the stack. And it may not apply to targets
like the AVR where strings get copied from flash to ram before use.
Back to comp.arch.embedded | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
arm-gcc: pointer to constant string pozz <pozzugno@gmail.com> - 2018-09-14 09:50 +0200
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-14 11:18 +0200
Re: arm-gcc: pointer to constant string pozz <pozzugno@gmail.com> - 2018-09-14 13:05 +0200
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-14 13:25 +0200
Re: arm-gcc: pointer to constant string Nils M Holm <nmh@ananda.local> - 2018-09-14 09:47 +0000
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-14 12:26 +0200
Re: arm-gcc: pointer to constant string Stef <stef33d@yahooI-N-V-A-L-I-D.com.invalid> - 2018-09-14 14:52 +0200
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-14 16:04 +0200
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-14 15:48 +0100
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-14 17:02 +0200
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-14 18:45 +0100
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-14 20:37 +0200
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-14 20:51 +0100
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-15 16:24 +0200
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-15 17:28 +0100
Re: arm-gcc: pointer to constant string Clifford Heath <no.spam@please.net> - 2018-09-16 13:58 +1000
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-16 08:42 +0100
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-16 08:47 +0100
Re: arm-gcc: pointer to constant string Clifford Heath <no.spam@please.net> - 2018-09-16 20:18 +1000
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-16 12:25 +0100
Re: arm-gcc: pointer to constant string Clifford Heath <no.spam@please.net> - 2018-09-16 22:22 +1000
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-16 15:00 +0200
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-16 14:33 +0100
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-16 22:06 +0200
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-16 21:42 +0100
Re: arm-gcc: pointer to constant string Les Cargill <lcargill99@comcast.com> - 2018-09-17 21:24 -0500
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-18 08:49 +0200
Re: arm-gcc: pointer to constant string Les Cargill <lcargill99@comcast.com> - 2018-09-21 22:15 -0500
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-22 11:53 +0200
Testing (Was: arm-gcc: pointer to constant string) Jacob Sparre Andersen <jacob@jacob-sparre.dk> - 2018-09-22 12:16 +0200
Re: Testing (Was: arm-gcc: pointer to constant string) David Brown <david.brown@hesbynett.no> - 2018-09-22 13:31 +0200
Re: Testing (Was: arm-gcc: pointer to constant string) Clifford Heath <no.spam@please.net> - 2018-09-23 09:26 +1000
Re: arm-gcc: pointer to constant string Niklas Holsti <niklas.holsti@tidorum.invalid> - 2018-09-22 20:06 +0300
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-23 14:39 +0200
Re: arm-gcc: pointer to constant string Les Cargill <lcargill99@comcast.com> - 2018-09-22 13:50 -0500
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-23 15:21 +0200
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-23 16:06 +0100
Re: arm-gcc: pointer to constant string julio@diegidio.name - 2018-09-23 08:41 -0700
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-23 16:49 +0100
Re: arm-gcc: pointer to constant string julio@diegidio.name - 2018-09-23 08:56 -0700
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-23 18:20 +0100
Re: arm-gcc: pointer to constant string julio@diegidio.name - 2018-09-23 12:05 -0700
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-23 20:50 +0100
Re: arm-gcc: pointer to constant string Les Cargill <lcargill99@comcast.com> - 2018-09-23 12:04 -0500
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-23 18:27 +0100
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-23 19:37 +0200
Re: arm-gcc: pointer to constant string Jacob Sparre Andersen <jacob@jacob-sparre.dk> - 2018-09-24 12:53 +0200
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-24 13:49 +0200
Re: arm-gcc: pointer to constant string Les Cargill <lcargill99@comcast.com> - 2018-09-28 20:17 -0500
Re: arm-gcc: pointer to constant string Tom Gardner <spamjunk@blueyonder.co.uk> - 2018-09-18 08:32 +0100
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-18 10:02 +0200
Re: arm-gcc: pointer to constant string Les Cargill <lcargill99@comcast.com> - 2018-09-21 22:17 -0500
Re: arm-gcc: pointer to constant string Stef <stef33d@yahooI-N-V-A-L-I-D.com.invalid> - 2018-09-14 18:30 +0200
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-14 20:46 +0200
Re: arm-gcc: pointer to constant string Stefan Reuther <stefan.news@arcor.de> - 2018-09-14 19:57 +0200
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-14 20:56 +0200
Re: arm-gcc: pointer to constant string Stefan Reuther <stefan.news@arcor.de> - 2018-09-15 18:32 +0200
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-16 15:06 +0200
Re: arm-gcc: pointer to constant string Richard Damon <Richard@Damon-Family.org> - 2018-09-14 19:59 -0400
Re: arm-gcc: pointer to constant string David Brown <david.brown@hesbynett.no> - 2018-09-15 16:25 +0200
Re: arm-gcc: pointer to constant string Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-09-14 13:49 +0300
csiph-web