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Internet Message Format | 1996-08-05 | 2.6 KB

Path: gate.net!pslfl2-47
From: [e-mail] (William Hutto)
Newsgroups: comp.lang.c
Subject: Re: gets() question
Date: 9 Jan 1996 04:01:31 GMT
Organization: CyberGate, Inc.
Message-ID: <4cspar$[e-mail]>
References: <4cosgf$[e-mail]> <4cqkt8$[e-mail]> <[e-mail]>
NNTP-Posting-Host: pslfl2-47.gate.net
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In article <[e-mail]>,
   Lawrence Kirby <[e-mail]> wrote:
>In article <4cqkt8$[e-mail]> [e-mail] "William Hutto"
writes:
>
>>In article <4cosgf$[e-mail]>,
>
>>>#include "stdio.h"
>
>Should be:
>
>#include <stdio.h>
>
>if you want to be sure to include the standard system stdio.h header.
>
>>>void main(void)
>
>Read the FAQ.
>
>>>{
>>>   int i[5];
>>>   char s[3][10];
>>>
>>>   printf ("Enter s[0]:  ");
>>>   gets (s[0]);
>>          ^^^^
>>
>>Your compiler didn't generate an error?
>
>Why should it?
>
>>*s* is not an array of pointers to
>>arrays of chars as in argv[].
>
>True, s is an array of arrays of char. s[0] is an array of 10 chars.
>When used as an rvalue in an expression an array evaluates to a pointer to
>its first element i.e. a char * in this case.
>
>>Now I remember why I always like being explicit.
>>Try this:
>>
>>        fgets(&s[0][0],9,stdin);
>
>It is certainly better to use fgets rather than gets but you could have
>written:
>
>         fgets(s[0],sizeof s[0],stdin);
>
>s[0] is equivalent to &s[0][0] in this context and is arguably more
>readable. The length argument of fgets specifies the size of the array
>available in the first argument (which is 10 in this case) i.e. fgets will
>read a maximum of N-1 characters from the input stream and then terminate the
>sequence in the array with '\0'.
>
>>You can use a 2 dimensional char array, except that you have to be complete
>>in your form and s[0] is not. Because fgets() (or gets() for that matter) is
>>looking for an address, you need to oblige, hence the prefix of *&*.
>
>You need to read up on how arrays and pointers work in C. There are no such
>thing as 2 dimensional arrays, just arrays of arrays. Each element of the
>overall array is itself an array and behaves just like any other array.
>

One thing I liked about C was it's predictability. :) That was one little
quirk that I didn't remember. I tend to be explicit in the use of subscripts
or dereferencing, and so if I had knowledge of that, it must have slipped into
the bit bucket. I appreciate the clarification guys, and sorry for the
erroneous data.

Bill

"Whatcha got on?...Your mind?"