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Groups > comp.lang.c > #147487
| From | David Brown <david.brown@hesbynett.no> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: memcpy not memcpying? |
| Date | 2019-11-01 21:14 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <qpi3ne$ek2$1@dont-email.me> (permalink) |
| References | <2LVuF.7$BF1.0@fx26.iad> <qSVuF.94$kE3.74@fx36.iad> <qphblr$leg$1@dont-email.me> <DHWuF.1569$kt1.1295@fx46.iad> <lnsgn77bw2.fsf@kst-u.example.com> |
On 01/11/2019 18:19, Keith Thompson wrote:
> DFS <nospam@dfs.com> writes:
> [...]
>> printf("%d\n",sizeof(char*));
>> 8
>
> sizeof yields a result of type size_t. Use "%zu", not "%d".
>
> Using "%d" can appear to work depending on how arguments are passed, but
> it's unreliable.
>
> If remembering all the formats is too much trouble (it is for me
> sometimes), you can convert to a type that you know how to print
> and that you're confident is wide enough to hold the value:
>
> printf("%lu\n", (unsigned long)sizeof(char*));
>
Or in this case, since you can be reasonably sure pointers don't take
over 2 GB of memory (or even 32 KB, for portability to 16-bit systems),
you can use:
printf("%d\n", (int) sizeof(char *));
DFS - since you are using gcc, and have previously shown that you use
-Wall, it should give you a warning when the printf format does not
match the parameters. Pay attention to the warning, and get in the
habit of getting the parameter types correct. Whether you fix the
format characters or cast the parameters can depend a bit on how
portable the code should be and how lazy you are feeling, but you will
at least learn how you should do it when it matters.
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memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 08:42 -0400
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 08:49 -0400
Re: memcpy not memcpying? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-01 09:24 -0400
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 09:46 -0400
Re: memcpy not memcpying? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-01 09:49 -0400
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-01 10:19 -0700
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-01 21:14 +0100
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 17:16 -0400
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-01 22:42 +0000
Re: memcpy not memcpying? Richard Damon <Richard@Damon-Family.org> - 2019-11-01 21:10 -0400
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-02 11:36 +0000
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-02 02:15 -0700
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-02 13:04 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-02 13:43 +0000
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-02 17:24 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-02 17:00 +0000
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-02 13:06 -0700
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-02 21:05 +0000
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-02 22:40 +0000
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-02 15:59 -0700
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-02 23:47 +0000
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-02 18:22 -0700
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 13:27 +0000
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-03 17:46 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 17:20 +0000
Re: memcpy not memcpying? Manfred <noname@add.invalid> - 2019-11-03 19:44 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 19:36 +0000
Re: memcpy not memcpying? Manfred <noname@add.invalid> - 2019-11-03 22:57 +0100
Re: memcpy not memcpying? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-03 22:39 +0000
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-03 23:06 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 23:28 +0000
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-04 11:00 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-04 11:14 +0000
Re: memcpy not memcpying? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-04 11:22 +0000
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-04 13:10 +0100
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-04 10:03 -0800
Re: memcpy not memcpying? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-04 19:36 +0000
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-05 10:04 -0800
Re: memcpy not memcpying? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-04 20:58 -0800
Re: memcpy not memcpying? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-04 22:01 -0800
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-04 12:56 +0100
Re: memcpy not memcpying? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-04 09:50 -0500
Re: memcpy not memcpying? scott@slp53.sl.home (Scott Lurndal) - 2019-11-04 20:26 +0000
Re: memcpy not memcpying? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-11-04 04:34 -0800
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-04 13:05 +0000
Re: memcpy not memcpying? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-04 14:09 +0000
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-04 15:11 +0000
Re: memcpy not memcpying? Melzzzzz <Melzzzzz@zzzzz.com> - 2019-11-04 15:15 +0000
Re: memcpy not memcpying? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-04 15:43 +0000
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 20:20 +0000
Re: memcpy not memcpying? Ian Collins <ian-news@hotmail.com> - 2019-11-03 14:37 +1300
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 11:01 +0000
Re: memcpy not memcpying? Öö Tiib <ootiib@hot.ee> - 2019-11-03 04:03 -0800
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 12:52 +0000
Re: memcpy not memcpying? Öö Tiib <ootiib@hot.ee> - 2019-11-03 23:34 -0800
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-04 09:36 +0000
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-04 16:20 +0000
Re: memcpy not memcpying? Ian Collins <ian-news@hotmail.com> - 2019-11-04 07:46 +1300
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-03 12:26 -0800
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-03 17:31 +0100
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-03 17:05 +0000
Re: memcpy not memcpying? already5chosen@yahoo.com - 2019-11-03 09:14 -0800
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-03 12:32 -0800
Re: memcpy not memcpying? already5chosen@yahoo.com - 2019-11-03 14:59 -0800
Re: memcpy not memcpying? already5chosen@yahoo.com - 2019-11-03 15:19 -0800
Re: memcpy not memcpying? already5chosen@yahoo.com - 2019-11-03 17:00 -0800
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-02 11:16 -0400
Re: memcpy not memcpying? David Brown <david.brown@hesbynett.no> - 2019-11-02 17:26 +0100
Re: memcpy not memcpying? Barry Schwarz <schwarzb@delq.com> - 2019-11-01 06:39 -0700
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 09:56 -0400
Re: memcpy not memcpying? Barry Schwarz <schwarzb@delq.com> - 2019-11-01 12:39 -0700
Re: memcpy not memcpying? guinness.tony@gmail.com - 2019-11-01 06:49 -0700
Re: memcpy not memcpying? jak <nospam@please.ty> - 2019-11-01 20:40 +0100
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-01 14:26 +0100
Re: memcpy not memcpying? Keith Thompson <kst-u@mib.org> - 2019-11-01 10:22 -0700
Re: memcpy not memcpying? Bart <bc@freeuk.com> - 2019-11-01 19:44 +0000
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-01 21:31 +0100
Re: memcpy not memcpying? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-01 09:39 -0400
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-01 14:42 +0100
Re: memcpy not memcpying? James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-01 09:48 -0400
Re: memcpy not memcpying? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-11-01 06:47 -0700
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-01 14:58 +0100
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 10:22 -0400
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-01 18:38 +0100
Re: memcpy not memcpying? scott@slp53.sl.home (Scott Lurndal) - 2019-11-01 17:54 +0000
Re: memcpy not memcpying? Autist <autist69@gmail.com> - 2019-11-01 20:24 +0100
Re: memcpy not memcpying? DFS <nospam@dfs.com> - 2019-11-01 15:24 -0400
Re: memcpy not memcpying? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-01 23:19 +0000
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