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Groups > comp.lang.c > #148199
| From | Ben Bacarisse <ben.usenet@bsb.me.uk> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: sizeof object got by dereferencing uniniitalized pointer |
| Date | 2019-11-28 22:34 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <871rtr4om3.fsf@bsb.me.uk> (permalink) |
| References | (3 earlier) <qromtr$3o3$1@dont-email.me> <2119c5dc-fc01-4a74-93f4-8027c7cc210e@googlegroups.com> <c97a16bb-4384-5e83-2c2f-1099b62be653@hrosenau.de> <43093894-ed52-47de-85f4-eadd92a1499e@googlegroups.com> <7NTDF.74422$Jw6.61134@fx35.iad> |
Richard Damon <Richard@Damon-Family.org> writes:
<cut>
> But you could also have had
>
> int n = 10
>
> int (*buf)[n] = 0
>
> and sizeof *buf would still be 40
>
> buf is NOT evaluated.
The operand of sizeof is evaluated when its type is a variable length
array type (6.5.3.4 p2). gcc agrees:
$ cat t.c
#include <stdio.h>
#include <stdlib.h>
int exit_zero(void) { exit(EXIT_FAILURE); return 0; }
int main(void)
{
#ifdef VLA
int n = 10;
#else
#define n 10
#endif
int (*buf)[n];
printf("size = %zu\n", sizeof buf[exit_zero()]);
}
$ gcc -std=c99 t.c
$ ./a.out
size = 40
$ gcc -DVLA -std=c99 t.c
$ ./a.out
$
--
Ben.
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sizeof object got by dereferencing uniniitalized pointer "V.Subramanian, India" <subramanian100in@yahoo.com> - 2019-11-28 05:20 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-11-28 05:37 -0800
Re: sizeof object got by dereferencing uniniitalized pointer mark.bluemel@gmail.com - 2019-11-28 05:59 -0800
Re: sizeof object got by dereferencing uniniitalized pointer David Brown <david.brown@hesbynett.no> - 2019-11-28 15:51 +0100
Re: sizeof object got by dereferencing uniniitalized pointer Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2019-11-28 07:27 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Herbert Rosenau <nospam@hrosenau.de> - 2019-11-28 17:28 +0100
Re: sizeof object got by dereferencing uniniitalized pointer Thiago Adams <thiago.adams@gmail.com> - 2019-11-28 08:51 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-28 17:36 +0000
Re: sizeof object got by dereferencing uniniitalized pointer Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-28 16:37 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-29 01:27 +0000
Re: sizeof object got by dereferencing uniniitalized pointer Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-28 17:47 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Richard Damon <Richard@Damon-Family.org> - 2019-11-28 21:16 -0500
Re: sizeof object got by dereferencing uniniitalized pointer Keith Thompson <kst-u@mib.org> - 2019-11-29 00:38 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Richard Damon <Richard@Damon-Family.org> - 2019-11-29 09:03 -0500
Re: sizeof object got by dereferencing uniniitalized pointer Keith Thompson <kst-u@mib.org> - 2019-11-29 13:15 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Keith Thompson <kst-u@mib.org> - 2019-11-29 13:38 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-29 07:09 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-29 06:10 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Richard Damon <Richard@Damon-Family.org> - 2019-11-29 11:12 -0500
Re: sizeof object got by dereferencing uniniitalized pointer Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-12-01 09:32 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-29 07:39 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-29 22:00 +0000
Re: sizeof object got by dereferencing uniniitalized pointer Richard Damon <Richard@Damon-Family.org> - 2019-11-29 22:40 -0500
Re: sizeof object got by dereferencing uniniitalized pointer Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-30 11:19 +0000
Re: sizeof object got by dereferencing uniniitalized pointer Richard Damon <Richard@Damon-Family.org> - 2019-11-30 09:01 -0500
Re: sizeof object got by dereferencing uniniitalized pointer Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-12-01 10:28 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Richard Damon <Richard@Damon-Family.org> - 2019-11-28 12:49 -0500
Re: sizeof object got by dereferencing uniniitalized pointer Thiago Adams <thiago.adams@gmail.com> - 2019-11-28 11:26 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Richard Damon <Richard@Damon-Family.org> - 2019-11-28 17:19 -0500
Re: sizeof object got by dereferencing uniniitalized pointer Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-11-28 17:26 -0800
Re: sizeof object got by dereferencing uniniitalized pointer Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-28 22:34 +0000
Re: sizeof object got by dereferencing uniniitalized pointer Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-11-28 17:34 +0000
You gotta wonder why people say things like this! (Was: sizeof object got by dereferencing uniniitalized pointer) gazelle@shell.xmission.com (Kenny McCormack) - 2019-11-28 17:19 +0000
Re: sizeof object got by dereferencing uniniitalized pointer Keith Thompson <kst-u@mib.org> - 2019-11-28 14:55 -0800
Re: sizeof object got by dereferencing uniniitalized pointer "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-11-30 15:28 -0800
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