problem opening a file

[aldrin@xtra.co.nz]

I'm trying to run this code under windows xp sp2 using codeblocks v1.0
compiler with great difficulty.Ther e is no problem with running this
under KDevelop in linux. Any help would be greatly appreciated.


Enter an interesting string.
Too many cooks spoil the broth
Error opening C:\myfile.txt for writing. Program termnated.
This application has requested the Runtime to terminate it in an
unusual way.
Please contact the application's support team for more information.

Press ENTER to continue.
*************** *************** *************** *************** *************** ******
#include <stdio.h>
#include <stdlib.h>

int main()
{
char mystring[80];
int i = 0;
int lstr = 0;
int mychar = 0;
FILE *pfile = NULL;
char *filename = "C:\\myfile.txt ";

printf("\nEnter an interesting string.\n");
gets(mystring);

pfile = fopen(filename, "w");
if(pfile == NULL)
{
printf("Error opening %s for writing. Program termnated.",
filename);
abort();
}

lstr = strlen(mystring );
for(i=lstr -1; i >= 0; i--)
fputc(mystring[i], pfile);

fclose(pfile);

/*ope file for reading*/
pfile = fopen(filename, "r");
if(pfile == NULL)
{
printf("Error opening %s for reading. Program terminated.",
filename);
abort();
}

/*Read a character from the file and display it*/
while((mychar = fgetc(pfile)) != EOF)
putchar(mychar) ;
putchar('\n');

fclose(pfile);
remove(filename );

return 0;
}

[Mike Wahler]

Re: problem opening a file


<aldrin@xtra.co .nz> wrote in message
news:1139704997 .964354.32630@f 14g2000cwb.goog legroups.com...[color=blue]
> I'm trying to run this code under windows xp sp2 using codeblocks v1.0
> compiler with great difficulty.Ther e is no problem with running this
> under KDevelop in linux. Any help would be greatly appreciated.
>
>
> Enter an interesting string.
> Too many cooks spoil the broth
> Error opening C:\myfile.txt for writing. Program termnated.
> This application has requested the Runtime to terminate it in an
> unusual way.
> Please contact the application's support team for more information.[/color]

I don't see anything wrong with the code (other than the
use of the inherently dangerous 'gets()' function).

For some reason, the host system has refused to open your
output file. C can only tell you if the operation succeeded
or not, but not *why* it didn't succeed.

Some possible reasons for 'fopen()' to fail on Windows:
1. Disk is full
2. Disk failure
3. Insufficient access rights.
4. Disk is inaccessible (e.g. disconnected from a network)
5. File is already opened by another process, but not 'shared'.

How to deal with any of these issues (or others) is not
covered by the C language.

The message about 'terminate in an unusual way' reflects the
fact that you called the standard function 'abort()', which
is indeed not the 'normal' way to terminate a C program.
The 'normal' way is to have function 'main()' return control
to the host system. (Also see 'exit()')

-Mike

[Walter Roberson]

Re: problem opening a file

In article <1139704997.964 354.32630@f14g2 000cwb.googlegr oups.com>,
<aldrin@xtra.co .nz> wrote:[color=blue]
>I'm trying to run this code under windows xp sp2 using codeblocks v1.0
>compiler with great difficulty.Ther e is no problem with running this
>under KDevelop in linux. Any help would be greatly appreciated.[/color]
[color=blue]
>Enter an interesting string.
>Too many cooks spoil the broth
>Error opening C:\myfile.txt for writing. Program termnated.
>This application has requested the Runtime to terminate it in an
>unusual way.[/color]
[color=blue]
> char *filename = "C:\\myfile.txt ";[/color]
[color=blue]
> pfile = fopen(filename, "w");
> if(pfile == NULL)
> {
> printf("Error opening %s for writing. Program termnated.",
>filename);
> abort();
> }[/color]

The rest of the program does not matter, as it is clear that in
the fault case the abort() is what is terminating the program.

So you have a situation where under true windows, C:\myfile.txt
cannot be opened for writing, but under an emulator (?),
KDevelop in linux, it can be.

My guess would be that in the real windows XP system, your process
does not have authorization to create files directly in C:\
and that in KDevelop either there is no file permission testing
or else that the emulated C:\ is a directory that you happen to
have access to.

I would suggest replacing the printf() with perror() as that will
print out the error reason. perror() does not support %s formats
though, so either work around that or include <errno.h> and
use strerror().
--
All is vanity. -- Ecclesiastes

[Keith Thompson]

Re: problem opening a file

aldrin@xtra.co. nz writes:[color=blue]
> I'm trying to run this code under windows xp sp2 using codeblocks v1.0
> compiler with great difficulty.Ther e is no problem with running this
> under KDevelop in linux. Any help would be greatly appreciated.[/color]

I have no idea what "codeblocks " is, but if your problem actually
depends on that, then it's not something we can help you with here.
[color=blue]
> Enter an interesting string.
> Too many cooks spoil the broth
> Error opening C:\myfile.txt for writing. Program termnated.
> This application has requested the Runtime to terminate it in an
> unusual way.
> Please contact the application's support team for more information.
>
> Press ENTER to continue.[/color]

I don't see any serious problems that would necessarily explain the
symptoms you're seeing. I do see some serious problems, though.

The "This application has requested ..." message is presumably caused
by the call to abort(). There's no need to terminate the program so
drastically; exit(EXIT_FAILU RE) is just fine.

Error messages are normally printed to stdout, not stderr (but that's
not required).
[color=blue]
> #include <stdio.h>
> #include <stdlib.h>
>
> int main()
> {
> char mystring[80];
> int i = 0;
> int lstr = 0;
> int mychar = 0;
> FILE *pfile = NULL;
> char *filename = "C:\\myfile.txt ";[/color]

Obviously this file name is non-portable. On Linux, your program
would probably create a file in the current directory whose name is
C:\myfile.txt
Check whether that's a valid file name in the environment in which
your program runs. Do you have write permission on C:\? What happens
if you change the file name to just "myfile.txt " (i.e., create it in
the current directory)?

Note that any considerations about directories, path names, and the
meaning of a file name is system-specific. If you're still having
trouble, you might try a system-specific newsgroup.
[color=blue]
> printf("\nEnter an interesting string.\n");
> gets(mystring);[/color]

Never use gets(). Never. Never ever. For all practical purposes, it
*cannot* be used safely. (There are obscure circumstances in which it
can be used safely, but if you know enough to figure that out you know
enough not to use gets() anyway.)

See <http://www.c-faq.com/stdio/getsvsfgets.htm l>.
[color=blue]
> pfile = fopen(filename, "w");
> if(pfile == NULL)
> {
> printf("Error opening %s for writing. Program termnated.",
> filename);[/color]

On some systems, a failing fopen() *might* set a meaningful value for
errno. Try setting errno to 0 before the fopen() call, and checking
its value after the call; use perror() to print an error message
*only* if errno!=0. The result may or may not be meaningful (the
standard doesn't say anything about fopen()'s effect on errno). See
also <http://www.c-faq.com/misc/errno.html>.
[color=blue]
> abort();
> }
>
> lstr = strlen(mystring );[/color]

You use strlen(), but you don't have a "#include <string.h>". Turn up
the warning level on your compiler; it should be able to warn you
about this kind of thing.
[color=blue]
> for(i=lstr -1; i >= 0; i--)
> fputc(mystring[i], pfile);
>
> fclose(pfile);[/color]

You've just created a text file that isn't terminated by a new-line
character. Some implementations might require a new-line at the end
of every text file. (Yours probably doesn't, but if you care about
portability you should make sure it's there anyway).
[color=blue]
> /*ope file for reading*/
> pfile = fopen(filename, "r");
> if(pfile == NULL)
> {
> printf("Error opening %s for reading. Program terminated.",
> filename);
> abort();
> }
>
> /*Read a character from the file and display it*/
> while((mychar = fgetc(pfile)) != EOF)
> putchar(mychar) ;
> putchar('\n');
>
> fclose(pfile);
> remove(filename );[/color]

Misleading indentation. Only the "putchar(mychar );" is part of the
while loop. With correct indentation:

while((mychar = fgetc(pfile)) != EOF)
putchar(mychar) ;
putchar('\n');

fclose(pfile);
remove(filename );

Personally, I always use braces with control structures, even when
they're not required, so I'd write it as:

while((mychar = fgetc(pfile)) != EOF) {
putchar(mychar) ;
}
putchar('\n');

fclose(pfile);
remove(filename );
[color=blue]
> return 0;
> }[/color]

Since you're having a problem on the initial fopen() call, the rest of
your program isn't relevant to the problem. You could have narrowed
your program down to something much smaller before posting.

(The program uses a temporary file to reverse a string. I'm sure
you're aware that there are much easier ways to reverse a string.)

--
Keith Thompson (The_Other_Keit h) kst-u@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Aldrin Fabricius]

Re: problem opening a file

>I would suggest replacing the printf() with perror() as that will[color=blue]
>print out the error reason. perror() does not support %s formats
>though, so either work around that or include <errno.h> and
>use strerror().[/color]

I'll try the suggestions above and see how it goes. Thanks!

[Aldrin Fabricius]

Re: problem opening a file

Keith great advice!! In my excitement to post i forgot to mention that
i modified the code to point to /home/user/text.txt.
[color=blue]
>Never use gets(). Never. Never ever. For all practical purposes, it
>*cannot* be used safely. (There are obscure circumstances in which it
>can be used safely, but if you know enough to figure that out you know
>enough not to use gets() anyway.)[/color]

Ignorance is bliss!! I will go back to the drawing board atleast with
something to think about. Thanks for that.

[Aldrin Fabricius]

Re: problem opening a file

>Some possible reasons for 'fopen()' to fail on Windows:[color=blue]
>1. Disk is full
>2. Disk failure
>3. Insufficient access rights.
>4. Disk is inaccessible (e.g. disconnected from a network)
>5. File is already opened by another process, but not 'shared'.[/color]

Double checked all disk/s have plenty of space with the same error
popping up under different IDEs(Visual C++ .net, Dev C++)on more than
one PC, and using admin account didn't have any effect. Also tested on
PCs running locally without networking and couldn't really see anything
that couldve interfered with the file opening other than the shoddy
coding.
[color=blue]
> The 'normal' way is to have function 'main()' return control
>to the host system. (Also see 'exit()')[/color]
thanks for that advice taken.

[Kenneth Brody]

Re: problem opening a file

aldrin@xtra.co. nz wrote:
[...][color=blue]
> Error opening C:\myfile.txt for writing. Program termnated.[/color]
[...][color=blue]
> pfile = fopen(filename, "w");
> if(pfile == NULL)
> {
> printf("Error opening %s for writing. Program termnated.",
> filename);[/color]

Try changing the above to:

perror(filename );

Although, as I understand it, the standard does not require fopen() to
set errno, your system probably does, so the above will probably print
the filename and the reason for the failure.

If, for some reason, your system doesn't set errno, then you'll have to
do some further investigation to find the cause.
[color=blue]
> abort();
> }[/color]
[...]


--
+-------------------------+--------------------+-----------------------------+
| Kenneth J. Brody | www.hvcomputer.com | |
| kenbrody/at\spamcop.net | www.fptech.com | #include <std_disclaimer .h> |
+-------------------------+--------------------+-----------------------------+
Don't e-mail me at: <mailto:ThisIsA SpamTrap@gmail. com>

[Kenneth Brody]

Re: problem opening a file

Walter Roberson wrote:
[...][color=blue]
> So you have a situation where under true windows, C:\myfile.txt
> cannot be opened for writing, but under an emulator (?),
> KDevelop in linux, it can be.[/color]
[...]

FYI -- "C:\myfile. txt" is a valid filename under Linux, so there may not
be any emulator involved. (Why anyone would want such a filename under
Linux is a separate issue.)

--
+-------------------------+--------------------+-----------------------------+
| Kenneth J. Brody | www.hvcomputer.com | |
| kenbrody/at\spamcop.net | www.fptech.com | #include <std_disclaimer .h> |
+-------------------------+--------------------+-----------------------------+
Don't e-mail me at: <mailto:ThisIsA SpamTrap@gmail. com>

[CBFalconer]

Re: problem opening a file

Kenneth Brody wrote:[color=blue]
> Walter Roberson wrote:
> [...][color=green]
> > So you have a situation where under true windows, C:\myfile.txt
> > cannot be opened for writing, but under an emulator (?),
> > KDevelop in linux, it can be.[/color]
> [...]
>
> FYI -- "C:\myfile. txt" is a valid filename under Linux, so there
> may not be any emulator involved. (Why anyone would want such a
> filename under Linux is a separate issue.)[/color]

Is an escaped m a legitimate string character? I could understand
your statement about "C:\noxious.txt ", "C:\bullturd.tx t", or
"C:\ambivalent. txt". Use of "C:\truncate.tx t" is likely to cause
future difficulties.

--
"If you want to post a followup via groups.google.c om, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers." - Keith Thompson
More details at: <http://cfaj.freeshell. org/google/>
Also see <http://www.safalra.com/special/googlegroupsrep ly/>

[Keith Thompson]

Re: problem opening a file

CBFalconer <cbfalconer@yah oo.com> writes:[color=blue]
> Kenneth Brody wrote:[color=green]
>> Walter Roberson wrote:
>> [...][color=darkred]
>> > So you have a situation where under true windows, C:\myfile.txt
>> > cannot be opened for writing, but under an emulator (?),
>> > KDevelop in linux, it can be.[/color]
>> [...]
>>
>> FYI -- "C:\myfile. txt" is a valid filename under Linux, so there
>> may not be any emulator involved. (Why anyone would want such a
>> filename under Linux is a separate issue.)[/color]
>
> Is an escaped m a legitimate string character? I could understand
> your statement about "C:\noxious.txt ", "C:\bullturd.tx t", or
> "C:\ambivalent. txt". Use of "C:\truncate.tx t" is likely to cause
> future difficulties.[/color]

No, "\m" is not legal in a C string literal, but the original program
had "C:\\myfile.txt "; since then, I think we've been using
"C:\myfile.txt" , not interpreted as a C string literal, to refer to
the name.

--
Keith Thompson (The_Other_Keit h) kst-u@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Lew Pitcher]

Re: problem opening a file

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

CBFalconer wrote:[color=blue]
> Kenneth Brody wrote:[color=green]
>> Walter Roberson wrote:
>> [...][color=darkred]
>>> So you have a situation where under true windows, C:\myfile.txt
>>> cannot be opened for writing, but under an emulator (?),
>>> KDevelop in linux, it can be.[/color]
>> [...]
>>
>> FYI -- "C:\myfile. txt" is a valid filename under Linux, so there
>> may not be any emulator involved. (Why anyone would want such a
>> filename under Linux is a separate issue.)[/color]
>
> Is an escaped m a legitimate string character?[/color]

FWIW, the OP's code didn't escape the 'm' of "myfile". Instead, it included an
escape for the '\'

OP> char *filename = "C:\\myfile.txt ";
...
OP> pfile = fopen(filename, "w");
...
OP> printf("Error opening %s for writing. Program termnated.",fil ename);

I believe that Kenneth's comment was made wrt the final filename, after the
escape sequence had been resolved.

[snip]

- --
Lew Pitcher

Master Codewright & JOAT-in-training | GPG public key available on request
Registered Linux User #112576 (http://counter.li.org/)
Slackware - Because I know what I'm doing.
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