Error with fgets

[blindsey]

Trying to use c for the first time in years and blowing out in fgets.

I created this very simple program which still produces the error:

#include <stdio.h>

int main(int argc, char *argv[])
{
FILE *fp1;
char *text1;

fgets(text1,150 ,stdin);
fputs(text1,std out);
return(0);
}

The error is "The instruction at "0x78022901 " referenced memory at
"0x00000003 ". The memory could not be "written"." I get it after
typing in some text and hitting enter.

I'm using gcc.

[Peter Nilsson]

Re: Error with fgets

blindsey wrote:

Trying to use c for the first time in years and blowing out in fgets.
>
I created this very simple program which still produces the error:
>
#include <stdio.h>
>
int main(int argc, char *argv[])
{
FILE *fp1;
char *text1;
>
fgets(text1,150 ,stdin);
fputs(text1,std out);
return(0);

BTW, you don't need parentheses in this return statement.

}

http://c-faq.com/aryptr/aryptr2.html

--
Peter

[blindsey]

Re: Error with fgets

On Apr 15, 7:06 pm, Peter Nilsson <ai...@acay.com .auwrote:

blindsey wrote:

Trying to use c for the first time in years and blowing out in fgets.

>

I created this very simple program which still produces the error:

>

#include <stdio.h>

>

       int main(int argc, char *argv[])
       {
         FILE *fp1;
         char *text1;

>

         fgets(text1,150 ,stdin);
         fputs(text1,std out);
         return(0);

>
BTW, you don't need parentheses in this return statement.
>

       }

>
 http://c-faq.com/aryptr/aryptr2.html
>
--
Peter

Thanks!

Ah, in the old days I never would have ...

Like I said, it had been a while.

[Bartc]

Re: Error with fgets


"blindsey" <blindsey@dsicd i.comwrote in message
news:ff029a70-ed6b-49a7-9aab-6505af1c8ab2@p2 5g2000hsf.googl egroups.com...

Trying to use c for the first time in years and blowing out in fgets.
>
I created this very simple program which still produces the error:
>
#include <stdio.h>
>
int main(int argc, char *argv[])
{
FILE *fp1;
char *text1;

You should initialise text1 here, to point to an array of at least 150
chars, or using malloc to allocate at least 150 chars.

Otherwise it will contain an arbitrary (and illegal) address. Such as
0x00000003.

fgets(text1,150 ,stdin);
fputs(text1,std out);
return(0);
}
>
The error is "The instruction at "0x78022901 " referenced memory at
"0x00000003 ". The memory could not be "written"." I get it after
typing in some text and hitting enter.
>
I'm using gcc.

--
Bart

[Morris Dovey]

Re: Error with fgets

blindsey wrote:

>
Trying to use c for the first time in years and blowing out in fgets.
>
I created this very simple program which still produces the error:
>
#include <stdio.h>
>
int main(int argc, char *argv[])
{
FILE *fp1;
char *text1;
>
fgets(text1,150 ,stdin);
fputs(text1,std out);
return(0);
}
>
The error is "The instruction at "0x78022901 " referenced memory at
"0x00000003 ". The memory could not be "written"." I get it after
typing in some text and hitting enter.
>
I'm using gcc.

You're telling the compiler that you want to read from stdin into
the memory area pointed to by text1.

You haven't initialized text1 to point anywhere in particular,
where do you suppose fgets is putting that data? (Hint: 'memory
at "0x00000003 "' probably doesn't belong to you.)

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA

http://www.iedu.com/DeSoto/

[D. Power]

Re: Error with fgets

In article
<ff029a70-ed6b-49a7-9aab-6505af1c8ab2@p2 5g2000hsf.googl egroups.com>,
blindsey <blindsey@dsicd i.comwrote:

Trying to use c for the first time in years and blowing out in fgets.
>
I created this very simple program which still produces the error:
>
#include <stdio.h>
>
int main(int argc, char *argv[])
{
FILE *fp1;
char *text1;

You haven't provided any memory for text1, you need to either allocate
memory for it, i.e.

text = malloc (150);

and don't forget to #include <stdlib.h>, or you need to declare text1 as
an array

char text1[150];

Regulars in this newsgroup will point out that using a magic number like
150 is considered bad practice, so it would be better to add

#define BUFFSIZE 150

or the like, then use it as

text = malloc (BUFSIZE);

etc.

>
fgets(text1,150 ,stdin);
fputs(text1,std out);
return(0);
}
>
The error is "The instruction at "0x78022901 " referenced memory at
"0x00000003 ". The memory could not be "written"." I get it after
typing in some text and hitting enter.
>
I'm using gcc.

HTH
DP

[Keith Thompson]

Re: Error with fgets

blindsey <blindsey@dsicd i.comwrites:

Trying to use c for the first time in years and blowing out in fgets.
>
I created this very simple program which still produces the error:
>
#include <stdio.h>
>
int main(int argc, char *argv[])
{
FILE *fp1;

You never initialize fp1, but that's ok since you never use it.

char *text1;

text1 is a pointer. You never initialize it, so it points to some
arbitrary location in memory -- or it doesn't point anywhere at all.

fgets(text1,150 ,stdin);

Now you're trying to read up to 150 bytes of information from stdin
into some unspecified location. Kaboom.

fputs(text1,std out);
return(0);
}
>
The error is "The instruction at "0x78022901 " referenced memory at
"0x00000003 ". The memory could not be "written"." I get it after
typing in some text and hitting enter.
>
I'm using gcc.

One fix would be to declare text1 as an array rather than as a
pointer. Another would be to allocate some memory for text1 to point
to, perhaps using malloc().

The comp.lang.c FAQ is at <http://www.c-faq.com/>. Reading the whole
thing probably wouldn't be a bad use of your time.

--
Keith Thompson (The_Other_Keit h) kst-u@mib.org <http://www.ghoti.net/~kst>
Nokia
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

[Flash Gordon]

Re: Error with fgets

blindsey wrote, On 15/04/08 23:58:

Trying to use c for the first time in years and blowing out in fgets.
>
I created this very simple program which still produces the error:
>
#include <stdio.h>
>
int main(int argc, char *argv[])
{
FILE *fp1;
char *text1;
>
fgets(text1,150 ,stdin);

<snip>

You have declared text1 as being a pointer, where does it point to? Go
to the comp.lang.c FAQ at http://c-faq.com/ and read about arrays and
pointers.
--
Flash Gordon

[CarlosB]

Re: Error with fgets

try this:

#include <stdio.h>

void main(void)
{
char text1[151]={0};

fgets(text1,siz eof(text1)-1,stdin);
fputs(text1,std out);
}

or, to save into a file whatever you type in the keyboard:

#include <stdio.h>

void main(void)
{
char text1[151]={0};
FILE *f;

fgets(text1,siz eof(text1)-1,stdin);
f=fopen("test.t xt","w");
if(f) {
fputs(text1,std out);
fclose(f);
}
}


there is a very alike example in: http://www.cplusplus.com/reference/c...dio/fputs.html

[]'s

[CarlosB]

Re: Error with fgets

try this:

#include <stdio.h>

void main(void)
{
char text1[151]={0};

fgets(text1,siz eof(text1)-1,stdin);
fputs(text1,std out);
}

or, to save into a file whatever you type in the keyboard:

#include <stdio.h>

void main(void)
{
char text1[151]={0};
FILE *f;

fgets(text1,siz eof(text1)-1,stdin);
f=fopen("test.t xt","w");
if(f) {
fputs(text1,f);
fclose(f);
}
}

there is a very alike example in: http://www.cplusplus.com/reference/c...dio/fputs.html

[]'s

[Keith Thompson]

Re: Error with fgets

CarlosB <carlosbar@gmai l.comwrites:

try this:
>
#include <stdio.h>
>
void main(void)

Wrong. Make it "int main(void)".

The comp.lang.c FAQ is at <http://c-faq.com/>. Read questions 11.12a
through 11.15. Then read the rest of it.

{
char text1[151]={0};

The initialization is harmless, but pointless since you immediately
read into text1.

fgets(text1,siz eof(text1)-1,stdin);

Why subtract 1? fgets reads at most N-1 characters; it stores them in
the buffer followed by a '\0'.

fputs(text1,std out);

return 0;

}

[...]

--
Keith Thompson (The_Other_Keit h) kst-u@mib.org <http://www.ghoti.net/~kst>
Nokia
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

[Peter Nilsson]

Re: Error with fgets

CarlosB wrote:

try this:
>
#include <stdio.h>
>
void main(void)

int main(void)

{
char text1[151]={0};
>
fgets(text1,siz eof(text1)-1,stdin);

if (!fgets(text1, sizeof text1, stdin))
{
/* error */
}

fputs(text1,std out);
}

--
Peter

[CBFalconer]

Re: Error with fgets

Flash Gordon wrote:

blindsey wrote:
>

>Trying to use c for the first time in years and blowing out in
>fgets. I created this very simple program which still produces
>the error:
>>
>#include <stdio.h>
>>
>int main(int argc, char *argv[]) {
> FILE *fp1;
> char *text1;
>>
> fgets(text1,150 ,stdin);

>
<snip>
>
You have declared text1 as being a pointer, where does it point
to? Go to the comp.lang.c FAQ at http://c-faq.com/ and read about
arrays and pointers.

Or, simpler, get ggets(), which is fully portable and written in
purely standard C. Available in source form at:

<http://cbfalconer.home .att.net/download/>

--
[mail]: Chuck F (cbfalconer at maineline dot net)
[page]: <http://cbfalconer.home .att.net>
Try the download section.


** Posted from http://www.teranews.com **

[vippstar@gmail.com]

Re: Error with fgets

On Apr 16, 8:17 am, CBFalconer <cbfalco...@yah oo.comwrote:

Flash Gordon wrote:

blindsey wrote:

>

Trying to use c for the first time in years and blowing out in
fgets. I created this very simple program which still produces
the error:

>

#include <stdio.h>

>

int main(int argc, char *argv[]) {
FILE *fp1;
char *text1;

>

fgets(text1,150 ,stdin);

>

<snip>

>

You have declared text1 as being a pointer, where does it point
to? Go to the comp.lang.c FAQ at http://c-faq.com/and read about
arrays and pointers.

>
Or, simpler, get ggets(), which is fully portable and written in
purely standard C. Available in source form at:
>
<http://cbfalconer.home .att.net/download/>

Reading the code in ggets.c I noticed that if you run out of memory
the byte read from the stream is dropped (lost). I suggest you use
ungetc() to push it back to the stream. Also, changing ix and cursize
to size_t wouldn't do any harm but good. (you can drop the casts in
realloc, and you'll be able to claim it's in standard C, since files
might have lines more than INT_MAX bytes long)

[CBFalconer]

Re: Error with fgets

vippstar@gmail. com wrote:

CBFalconer <cbfalco...@yah oo.comwrote:
>

.... snip ...

>>
>Or, simpler, get ggets(), which is fully portable and written in
>purely standard C. Available in source form at:
>>
> <http://cbfalconer.home .att.net/download/>

>
Reading the code in ggets.c I noticed that if you run out of memory
the byte read from the stream is dropped (lost). I suggest you use
ungetc() to push it back to the stream. Also, changing ix and cursize
to size_t wouldn't do any harm but good. (you can drop the casts in
realloc, and you'll be able to claim it's in standard C, since files
might have lines more than INT_MAX bytes long)

Good points. However, ggets only returns 0, 1, or EOF, which
requires exactly an int. I did put it in public domain, so go
ahead and make the changes. I have some doubts about the ungetc,
since once memory is no longer available it is possible that ungetc
no longer works.

--
[mail]: Chuck F (cbfalconer at maineline dot net)
[page]: <http://cbfalconer.home .att.net>
Try the download section.


** Posted from http://www.teranews.com **