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Groups > comp.lang.c > #105097
| From | David Brown <david.brown@hesbynett.no> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: writing a c program to substitute text |
| Date | 2017-02-28 14:38 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <o93ucu$3nv$1@dont-email.me> (permalink) |
| References | <ehfv4oFu00sU1@mid.individual.net> <6b1df453-b6df-3cf8-eb6e-255c37ef241a@verizon.net> <ehl892F1h4hU1@mid.individual.net> |
On 28/02/17 13:20, fred flintstone wrote:
> On 02/26/2017 03:55 PM, James R. Kuyper wrote:
>> On 02/26/2017 07:14 AM, fred flintstone wrote:
>> ...
>>> So there's 3DBESNUB type things ...
>>
>> Is this
>> <https://www.physics.byu.edu/faculty/christensen/Physics%20121/3D%20BE%20SNUB.htm>
>>
>> what you're referring to?
>
> Yeah. I'm trying to paint the pictures that I need to to make it around
> the bases on this one. Better usenet practice is when OP does not force
> readers to follow links, as these might be suspect. I'm left to paint a
> picture with words.
It is even better Usenet practice to explain what is relevant, in clear
terms appropriate to the group. Stop "painting pictures" and using
silly American sporting terms ("make it around the bases"). Just use
plain English. And while posting links is often bad, it is far worse to
use local acronyms such as your 3D-thingy that are meaningless to almost
everyone unless they spent time researching them.
>
> I want to draw the attention of respondents down here, as I announce
> myself safe on some type of first base, fulfilling D1 of the three D's.
> D1 might be a portrait of the client of the C application. The client
> is, first and foremost, me, and then everyone I take care of with the
> same methods. Many are simple pioneers, who don't need to be dished out
> to what's Out There.
The words may be spelt correctly, but you are writing gibberish. Please
stop. You will end up on killfiles or being ignored - and the people
who killfile you are mostly the people (like Richard Heathfield, who has
also warned you) who give good, solid answers in this group.
<snip>
>>>
>>> , how do I declare this string to exist safely?
>>
>> That depends upon which danger you're hoping to avoid. Define the
>> danger, and we can tell you the best way to minimize it. However, don't
>> expect too much. C is a very low-level language - it does very little to
>> protect you from shooting yourself in the foot. It's the language used
>> to efficiently implement many of the safer languages. Here's several
>> different options, each of which has different advantages and
>> disadvantages:
>>
>> #define ARROW "arrow"
>>
>> const char *parrow = "arrow";
>> char arrow[] = "arrow";
>> // Either of those definitions could be declared static
>> // Either of those definitions could appear at either file scope or
>> // block scope.
>>
>> parrow = malloc(sizeof "arrow"));
>> memcpy(parrow, "arrow", sizeof "arrow");
>>
>
> Listen to me james. Have you ever used 'malloc' as a verb? If you have a
> declaration like:
>
> const char *parrow = "arrow";
>
> , can one say that it has been malloced, or is it only correct to use
> the grown-up term of "allocated?" (Might there be a malloc right under
> the patina?)
Some people use malloc as a verb, others would say allocated on the heap
or dynamically allocated. No one would say that about "parrow" or
"arrow" above, because there has been no dynamic allocation.
>>> Do I malloc a 1000 because someone has to make an adult decision?
>>
>> That depends entirely upon what danger you're trying to protect against.
>> As a general rule, if that solution helps you avoid a danger, then that
>> danger involves bad coding practices. In that case, you're better off
>> avoiding that danger by by improving your coding practices than by
>> allocating 1000 bytes to hold a 5-character string.
>
> This source considers some minimal cases. I like to write quines.
> Douglas Hofstadter's Goedel Escher Bach set me back 44 marks, a lot of
> money to me.
More meaningless gibberish.
>
> Anyways, the idea is that the source is reproduced faithfully. I'm not
> doing it in a strict mathematical sense (yet). I'll begin with a source
> listing of the driving .sh, avec warnings, the output thereof, and then
> ask questions. So, tja:
>
> $ sh toolchain2.sh
> sub1.c: In function ‘main’:
> sub1.c:13:15: warning: unused variable ‘ext’ [-Wunused-variable]
> const char *ext = "sh";
> ^
> sub1.c:12:15: warning: unused variable ‘base’ [-Wunused-variable]
> const char *base = "toolchain";
> ^
> sub1.c:11:15: warning: unused variable ‘executable2’ [-Wunused-variable]
> const char *executable2 = "mahershala";
> ^
> sub1.c:10:15: warning: unused variable ‘executable1’ [-Wunused-variable]
> const char *executable1 = "arrow";
> ^
> sub1.c:8:7: warning: unused variable ‘version’ [-Wunused-variable]
> int version, c, i;
> ^
> $ pwd
> /home/bob/Documents/programming/Book Examples/ch02/command_line
> $ ls -l
> total 44
> -rw-rw-r-- 1 bob bob 1804 Feb 26 01:03 arrow.c
> -rw-rw-r-- 1 bob bob 1008 Feb 27 17:42 awk3
> -rwxrwxr-x 1 bob bob 9104 Feb 27 18:25 sub1
> -rw-rw-r-- 1 bob bob 950 Feb 27 18:24 sub1.c
> -rw-rw-r-- 1 bob bob 1030 Feb 27 18:15 sub1.c~
> -rw-rw-r-- 1 bob bob 969 Feb 27 18:25 text1.txt
> -rw-rw-r-- 1 bob bob 103 Feb 27 18:22 toolchain2.sh
> -rwxrwxr-x 1 bob bob 273 Feb 26 01:51 toolchain3.sh
> -rw-rw-r-- 1 bob bob 273 Feb 27 18:25 toolchain4.sh
> $ cat toolchain2.sh
> gcc -Wall -Wextra -o sub1 sub1.c >text1.txt
You should add "-O1" to that list - it lets gcc do better analysis for
more warnings.
> ./sub1 arrow mahershala >>text1.txt
> cat sub1.c >>text1.txt
> $ cat text1.txt
> 3
> arrow
> mahershala
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
>
> int
> main (int argc, char *argv[])
> {
> int version, c, i;
> FILE *fptr, *gptr;
> const char *executable1 = "arrow";
> const char *executable2 = "mahershala";
> const char *base = "toolchain";
> const char *ext = "sh";
>
>
>
> printf ("%d\n", argc);
> for (i = 1; i < argc; i++) {
> printf ("%s\n", argv[i]);
> }
> fptr = fopen ("toolchain3.sh", "r");
> if (fptr == NULL) {
> printf ("fopen no bueno");
> exit (1);
> }
> gptr = fopen ("toolchain4.sh", "w");
>
> if (gptr == NULL) {
> printf ("gopen no bueno");
> exit (1);
> }
>
> while (1) {
> c = fgetc (fptr);
>
> if (c == EOF)
> break;
> else
> putc (c, gptr);
> }
>
>
> fclose (fptr);
> fclose (gptr);
>
> return 0;
> }
>
Please remove Malcolm's useless "mytstdrdup" function from your code.
His post was not helpful in any way.
> char *
> mystdrdup (const char *str)
> {
> size_t len = strlen (str);
> char *answer = malloc (len + 1);
> if (answer)
> strcpy (answer, str);
> else { /* error handling here */
> };
>
> return answer;
> }
> $
>
> Q1) Is this standard, portable, contemporary C?
You have already been given a number of suggestions to improve the code,
including solving your original problem.
>
> Q2) This program shall be legal C. What constraints does that put on the
> cumulative size on what comes from argv?
It is up to the implementation to decide what comes in on argv.
>
> The specification of this program will handle the case that what is
> passed to it exceeds the allowable parameters. Is it INT_MIN?
You are not currently using anything that is passed to the program, and
we have no way of guessing what that might be, or what your
specifications are.
>
> Q3) I have Plauger's _Standard C Library_ under my bed somewhere. How
> would the list of necessary .h files differ from then to contemporary C?
I don't know that book. There are plenty of references for modern
standard C headers. The ultimate reference is the C standards - N1570
is a freely available draft of C11. But the standards documents are not
easily going for a beginner. I would recommend this site:
<http://en.cppreference.com/w/c/header>
The C FAQ at <http://c-faq.com/> is also an excellent reference.
>
> Thank you for your comment, and remember, some people warm up to a
> topic....
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writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-02-26 04:14 -0800
Re: writing a c program to substitute text fir <profesor.fir@gmail.com> - 2017-02-26 04:55 -0800
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-26 14:28 +0100
Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-02-27 03:58 -0800
Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-27 13:11 +0000
Re: writing a c program to substitute text BartC <bc@freeuk.com> - 2017-02-27 13:33 +0000
Re: writing a c program to substitute text scott@slp53.sl.home (Scott Lurndal) - 2017-02-27 17:12 +0000
Re: writing a c program to substitute text BartC <bc@freeuk.com> - 2017-02-27 17:59 +0000
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 19:05 +0100
Re: writing a c program to substitute text scott@slp53.sl.home (Scott Lurndal) - 2017-02-27 18:37 +0000
Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-27 11:40 -0800
Re: writing a c program to substitute text Manfred <noname@invalid.add> - 2017-02-27 16:03 +0100
Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-03-01 05:33 -0800
Re: writing a c program to substitute text "D. Aaron Sawyer" <aaron@110.net> - 2017-03-01 10:32 -0400
Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-03-01 06:59 -0800
Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-01 15:24 +0000
Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-03-02 01:47 -0800
Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-02 11:05 +0000
Re: writing a c program to substitute text jt@toerring.de (Jens Thoms Toerring) - 2017-02-27 13:33 +0000
Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-27 09:10 -0800
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 19:07 +0100
Re: writing a c program to substitute text jt@toerring.de (Jens Thoms Toerring) - 2017-02-27 18:23 +0000
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 14:46 +0100
Re: writing a c program to substitute text James Kuyper <jameskuyper@verizon.net> - 2017-02-27 09:27 -0500
Re: writing a c program to substitute text GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-02-27 15:28 +0100
Re: writing a c program to substitute text James Kuyper <jameskuyper@verizon.net> - 2017-02-27 09:38 -0500
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 15:44 +0100
Re: writing a c program to substitute text James Kuyper <jameskuyper@verizon.net> - 2017-02-27 10:36 -0500
Re: writing a c program to substitute text Anglican <h.toms@qmul.ac.uk> - 2017-02-27 15:50 +0000
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 17:13 +0100
Re: writing a c program to substitute text Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-27 16:30 -0800
Re: writing a c program to substitute text fir <profesor.fir@gmail.com> - 2017-02-27 07:08 -0800
Re: writing a c program to substitute text fir <profesor.fir@gmail.com> - 2017-02-27 07:20 -0800
Re: writing a c program to substitute text fir <profesor.fir@gmail.com> - 2017-02-27 07:24 -0800
Re: writing a c program to substitute text Manfred <noname@invalid.add> - 2017-02-27 16:00 +0100
Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-27 09:22 -0800
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 19:11 +0100
Re: writing a c program to substitute text John Bode <jfbode1029@gmail.com> - 2017-02-28 15:41 -0800
solved Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-03-02 01:25 -0800
Re: solved Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-03-02 11:28 +0100
Re: solved Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-02 10:54 +0000
Re: solved Re: writing a c program to substitute text Manfred <noname@invalid.add> - 2017-03-02 15:28 +0100
Re: solved Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-02 14:51 +0000
Re: solved Re: writing a c program to substitute text John Bode <jfbode1029@gmail.com> - 2017-03-02 14:18 -0800
Re: solved Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-03-02 23:55 +0000
Re: solved Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-03-14 18:32 -0700
Re: writing a c program to substitute text Tim Rentsch <txr@alumni.caltech.edu> - 2017-04-17 07:04 -0700
Re: writing a c program to substitute text jladasky@itu.edu - 2017-02-27 13:48 -0800
Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-02-27 14:16 -0800
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-28 08:47 +0100
Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-02-28 01:59 -0800
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-28 11:39 +0100
Re: writing a c program to substitute text Richard Heathfield <rjh@cpax.org.uk> - 2017-02-28 12:03 +0000
Re: writing a c program to substitute text BartC <bc@freeuk.com> - 2017-02-28 13:33 +0000
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-28 14:43 +0100
Re: writing a c program to substitute text BartC <bc@freeuk.com> - 2017-02-28 13:59 +0000
Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-03-01 04:26 -0800
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 23:29 +0100
Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-27 15:10 -0800
Re: writing a c program to substitute text Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-26 06:42 -0800
Re: writing a c program to substitute text Richard Heathfield <rjh@cpax.org.uk> - 2017-02-26 16:54 +0000
[OT] "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2017-02-27 00:56 +0800
Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-26 13:36 -0800
Re: writing a c program to substitute text Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-26 14:53 -0800
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 00:53 +0100
Re: writing a c program to substitute text Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-26 17:30 -0800
Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-26 17:44 -0800
Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-27 01:46 +0000
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 09:29 +0100
Re: writing a c program to substitute text Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-27 02:12 -0800
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-27 13:11 +0100
Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-02-27 04:41 -0800
Re: writing a c program to substitute text Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-27 05:04 -0800
Re: writing a c program to substitute text Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-27 13:25 +0000
Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-27 09:56 -0800
Re: writing a c program to substitute text "Mr. Man-wai Chang" <toylet.toylet@gmail.com> - 2017-02-27 01:00 +0800
Re: writing a c program to substitute text "James R. Kuyper" <jameskuyper@verizon.net> - 2017-02-26 18:55 -0500
Re: writing a c program to substitute text fred flintstone <fred@server.invalid> - 2017-02-28 04:20 -0800
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-28 14:38 +0100
Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-28 08:33 -0800
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-28 19:38 +0100
Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-28 11:40 -0800
Re: writing a c program to substitute text David Brown <david.brown@hesbynett.no> - 2017-02-28 21:03 +0100
Re: gcc optimization levels Noob <root@127.0.0.1> - 2017-02-28 22:55 +0100
Re: writing a c program to substitute text "James R. Kuyper" <jameskuyper@verizon.net> - 2017-02-28 11:43 -0500
Re: writing a c program to substitute text Keith Thompson <kst-u@mib.org> - 2017-02-28 08:46 -0800
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