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Groups > comp.lang.c > #100885
| From | Noob <root@127.0.0.1> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Using == operator |
| Date | 2017-01-02 19:03 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <o4e4i6$bna$1@dont-email.me> (permalink) |
| References | <4598b1a6-e647-4327-85d8-23f83198d0c6@googlegroups.com> <o4djuk$ebt$1@dont-email.me> <o4dkf4$g93$1@dont-email.me> <o4dvdt$nnb$1@dont-email.me> <true-20170102181321@ram.dialup.fu-berlin.de> |
On 02/01/2017 18:13, Stefan Ram wrote:
> Noob <root@127.0.0.1> writes:
>>> if (q = NULL) ...
>> ^^^
>> Fail ;-)
>
> And we also should not forget another possibility
> of how the friends of »==« might fail!
>
> Can you spot the (potential) error in the following
> program?
>
> #include <ctype.h>
> #include <stdio.h>
> #include <stdbool.h>
>
> int main( void )
> { if( isprint( 20 )== true )
isprint() returns zero/nonzero.
'true' might be a different nonzero.
if (isprint(x) != 0) ...
if (isprint(x)) ...
In my opinion, pointers are not booleans, and should be compared
to a pointer.
if (p == NULL) ...
if (q != NULL) ...
Regards.
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guidelines for pointer check Thiago Adams <thiago.adams@gmail.com> - 2016-12-29 12:53 -0800
Re: guidelines for pointer check Ian Collins <ian-news@hotmail.com> - 2016-12-30 09:58 +1300
Re: guidelines for pointer check Keith Thompson <kst-u@mib.org> - 2016-12-29 13:39 -0800
Re: guidelines for pointer check Thiago Adams <thiago.adams@gmail.com> - 2016-12-29 15:24 -0800
Re: guidelines for pointer check Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2016-12-29 19:05 -0500
Re: guidelines for pointer check Thiago Adams <thiago.adams@gmail.com> - 2016-12-30 05:27 -0800
Re: guidelines for pointer check Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-12-30 14:35 +0000
Re: guidelines for pointer check supercat@casperkitty.com - 2016-12-30 10:38 -0800
Re: guidelines for pointer check Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-02 02:28 -0800
Re: guidelines for pointer check Keith Thompson <kst-u@mib.org> - 2016-12-29 16:19 -0800
Re: guidelines for pointer check Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-12-29 13:58 -0800
guidelines for pointer check asetofsymbols@gmail.com - 2016-12-30 05:35 -0800
Re: guidelines for pointer check raltbos@xs4all.nl (Richard Bos) - 2017-01-01 10:47 +0000
Re: guidelines for pointer check Noob <root@127.0.0.1> - 2017-01-02 14:19 +0100
Re: guidelines for pointer check David Brown <david.brown@hesbynett.no> - 2017-01-02 14:28 +0100
Re: guidelines for pointer check Noob <root@127.0.0.1> - 2017-01-02 17:35 +0100
Re: Using == operator Noob <root@127.0.0.1> - 2017-01-02 19:03 +0100
Re: Using == operator David Brown <david.brown@hesbynett.no> - 2017-01-02 23:41 +0100
Re: Using == operator Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-02 14:54 -0800
Re: Using == operator Keith Thompson <kst-u@mib.org> - 2017-01-02 15:57 -0800
Re: Using == operator Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2017-01-03 16:31 -0500
Re: Using == operator Keith Thompson <kst-u@mib.org> - 2017-01-03 14:06 -0800
Re: Using == operator Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-03 14:44 -0800
Re: Using == operator Keith Thompson <kst-u@mib.org> - 2017-01-03 15:05 -0800
Re: Using == operator Jorgen Grahn <grahn+nntp@snipabacken.se> - 2017-01-04 16:42 +0000
Re: Using == operator Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-15 11:46 -0800
Re: Using == operator Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-01-03 21:22 -0700
Re: Using == operator supercat@casperkitty.com - 2017-01-03 15:23 -0800
Re: Using == operator Keith Thompson <kst-u@mib.org> - 2017-01-03 15:30 -0800
Re: Using == operator supercat@casperkitty.com - 2017-01-03 16:02 -0800
Re: Using == operator Keith Thompson <kst-u@mib.org> - 2017-01-03 16:30 -0800
Re: Using == operator Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-15 11:26 -0800
Re: Using == operator raltbos@xs4all.nl (Richard Bos) - 2017-01-04 09:55 +0000
Re: Using == operator Jorgen Grahn <grahn+nntp@snipabacken.se> - 2017-01-04 16:49 +0000
Re: Using == operator raltbos@xs4all.nl (Richard Bos) - 2017-01-10 01:28 +0000
Re: Using == operator Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-01-09 19:12 -0700
Re: Using == operator Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-15 09:12 -0800
Re: Using == operator Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-15 09:54 -0800
Re: Using == operator raltbos@xs4all.nl (Richard Bos) - 2017-01-03 21:08 +0000
Re: Using == operator Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-15 06:44 -0800
Re: guidelines for pointer check Anand Hariharan <mailto.anand.hariharan@gmail.com> - 2017-01-04 08:54 -0800
Re: guidelines for pointer check Tim Rentsch <txr@alumni.caltech.edu> - 2017-01-14 00:51 -0800
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