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From: mccaugh@s.cs.uiuc.edu
Newsgroups: comp.lang.c
Subject: Re: strcat/access question
Message-ID: <207600049@s.cs.uiuc.edu>
Date: 4 Oct 89 07:13:00 GMT
References: <5409@umd5.umd.edu>
Lines: 29
Nf-ID: #R:umd5.umd.edu:5409:s.cs.uiuc.edu:207600049:000:1037
Nf-From: s.cs.uiuc.edu!mccaugh    Oct  4 02:13:00 1989


> Here is a section of code:
> 
> if((home=getenv("HOME"))==(char *) 0)
>     perror("GETENV\n");
> printf("%s:\n", home);
> printf("%s:\n", strcpy(string,strcat(home, "/astro/data/obs.list")));
> printf("%s:\n", string);
> printf("%d:\n", access(string, 4));
> printf("%d:\n", access(strcat(home, "/astro/data/obs.list"), 4));
> 
> And the associated output:
> 
> /a/jjk:
> /a/jjk/astro/data/obs.list:
> /a/jjk/astro/data/obs.list:
> 0:
> -1:
> 
> The man page says that strcat returns a null-terminated string so that
> the two calls to access (I think) should both give "0" but the second
> is saying the file doesn't exist.  

 Actually, I recall the 'man' page stating that strcat returns a pointer
 (char-type) to the null-terminated string, but in any case I suspect
 that the last printf contains a call to strcat which assigns to your
 string-variable 'home' the name of a truly non-existent file, namely:
 "/a/jjk/astro/data/obs.list/astro/data/obs.list", so a redundant 'strcat'
 appears to have occurred in variable 'home'.