Re: ?Comparison always 0|1 ....???

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Article #50536

#50536

From: D. Erway
Date: Tue, 21 Sep 1993 18:42

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>>>>> On 17 Sep 1993 21:07:44 GMT, jgraf@lsil.com (Jim Graf) said:

 jgraf> Using gcc-2.3.3 on SunOS 4.1.3 I have been seeing these types of
 jgraf> warnings: ftpd.c: In function `makedir': ftpd.c:2151: warning:
 jgraf> comparison is always 1 due to limited range of data type

 jgraf> the code is:
 jgraf> makedir(char *name)
 jgraf> {
 jgraf>    uid_t uid = (uid_t) -1;
 jgraf>    gid_t gid = (gid_t) -1;
 jgraf>    uid_t oldid;
 jgraf> [deleted... ]
 jgraf>     if (uid >= 0) {            <-------- the offending line...
 jgraf> [deleted...]
 jgraf>     }

 jgraf> and uid_t is defined as unsigned short in /usr/include/sys/types.h

an unsigned value can NEVER be less than 0, therefore it is ALWAYS greater
than or equal to 0.

Also, setting them to -1 is actually setting them to 0xffff.

	-DOn

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From: derway@alumni.cco.caltech.edu (D. Erway)
Newsgroups: gnu.gcc.help
Subject: Re: ?Comparison always 0|1 ....???
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Date: 21 Sep 1993 18:42:20 GMT
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In-reply-to: jgraf@lsil.com's message of 17 Sep 1993 21:07:44 GMT

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