parsing a file error

[Medvedev]

when i try to read the first byte from an EXE file it's give different
results
code:
FILE *me,*u;
char buf_me[1];
char buf_u[1];

me= fopen(argv[0],"rb");
u= fopen(argv[1],"rb+");

fread(buf_me,sizeof(char),1,me);
fread(buf_u,sizeof(char),1,u);

printf("%s\n",buf_me);
printf("%s\n",buf_u);

----
when you run this code and put EXE file as an argument , the program
will print
M
MM

why it double the byte in the second time

[Dand]

"Medvedev" <3D********@gmail.comwrote in message
news:7b**********************************@27g2000h sf.googlegroups.com...

when i try to read the first byte from an EXE file it's give different
results
code:
FILE *me,*u;
char buf_me[1];
char buf_u[1];

me= fopen(argv[0],"rb");
u= fopen(argv[1],"rb+");

fread(buf_me,sizeof(char),1,me);
fread(buf_u,sizeof(char),1,u);

printf("%s\n",buf_me);
printf("%s\n",buf_u);

You are not terminating your strings with nulls. Make your buf's 2 bytes and
set the second byte to \0.
Also you should be checking the return values of fopen. If you are opening
the same file with both calls, most likly the second fopen call will be
failing. On many systems you won't be able to open argv[0] successfully at
all. You should also check your return values of fread. Also you are using
%s to print data that is probably going to be binary, not printable text
characters.

[rahul]

On Jul 1, 12:37 pm, "Dand" <[e-mail]:

If you are opening
the same file with both calls, most likly the second fopen call will be
failing. On many systems you won't be able to open argv[0] successfully at
all.

Both of them seem to work under Linux/gcc.

[Robbie Hatley]

"Medvedev" boggled my mind thusly:

when i try to read the first byte from an EXE file it's give different
results
code:
FILE *me,*u;
char buf_me[1];
char buf_u[1];

me= fopen(argv[0],"rb");
u= fopen(argv[1],"rb+");

fread(buf_me,sizeof(char),1,me);
fread(buf_u,sizeof(char),1,u);

printf("%s\n",buf_me);
printf("%s\n",buf_u);

----

Best not to put strings of hyphens in usenet posts; it can
confuse some software into thinking it's a signature separator.

when you run this code and put EXE file as an argument ,
the program will print:
M
MM

why it double the byte in the second time

A string with n bytes needs a char array with at least n+1 bytes,
with the first unused byte set to 0.

Google("null-terminated string").

But if you only have 1 character, why use strings at all? Use
characters:

FILE *me = NULL;
FILE *u = NULL;
char buf_me = 0;
char buf_u = 0;

me = fopen ( argv[0], "rb" );
u = fopen ( argv[1], "rb+" );

fread ( &buf_me, 1, 1, me );
fread ( &buf_u, 1, 1, u );

printf ( "%c\n", buf_me );
printf ( "%c\n", buf_u );

--
Cheers,
Robbie Hatley
lonewolf aatt well dott com
www dott well dott com slant user slant lonewolf slant

[CBFalconer]

Robbie Hatley wrote:

"Medvedev" boggled my mind thusly:

.... snip ...

>

> printf("%s\n",buf_me);
printf("%s\n",buf_u);

----

Best not to put strings of hyphens in usenet posts; it can
confuse some software into thinking it's a signature separator.

No problem. A sig marker is precisely "-- ", with no extra chars.

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

[Richard Heathfield]

CBFalconer said:

Robbie Hatley wrote:

>"Medvedev" boggled my mind thusly:

... snip ...

>>

>> printf("%s\n",buf_me);
printf("%s\n",buf_u);

----

Best not to put strings of hyphens in usenet posts; it can
confuse some software into thinking it's a signature separator.

No problem. A sig marker is precisely "-- ", with no extra chars.

If you think that we can rely on newsreaders to get this right and not be
confused into misreading a hyphen-string ---- as a signature separator,
presumably you also agree that we can rely on compilers to get
initialisation right?

--
Richard Heathfield <http://www.cpax.org.uk>
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

[santosh]

CBFalconer wrote:

Robbie Hatley wrote:

>"Medvedev" boggled my mind thusly:

... snip ...

>>

>> printf("%s\n",buf_me);
printf("%s\n",buf_u);

----

Best not to put strings of hyphens in usenet posts; it can
confuse some software into thinking it's a signature separator.

No problem. A sig marker is precisely "-- ", with no extra chars.

To be precise, a sig separator is '\n-- \n'

[jaysome]

On Thu, 03 Jul 2008 12:44:19 +0530, santosh <sa*********@gmail.com>
wrote:

>CBFalconer wrote:

>Robbie Hatley wrote:

>>"Medvedev" boggled my mind thusly:

... snip ...

>>>
printf("%s\n",buf_me);
printf("%s\n",buf_u);

----

Best not to put strings of hyphens in usenet posts; it can
confuse some software into thinking it's a signature separator.

No problem. A sig marker is precisely "-- ", with no extra chars.

To be precise, a sig separator is '\n-- \n'

To be precise, in Standard C, which is the topic of this newsgroup, a
sig separator is:

"\n-- \n"

/* start of sig */
#include <stdio.h>
#define SIG_SEPARATOR "\n-- \n"
int main(void)
{
printf("%sjay", SIG_SEPARATOR);
return 0;
}
/* end of sig */