From:	"John M. Aldrich" <fighteer AT cs DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: how do I read files ???
Date:	Sat, 12 Oct 1996 02:35:59 -0700
Organization:	Three pounds of chaos and a pinch of salt
Lines:	91
Message-ID:	<325F667F.7F15@cs.com>
References:	<199610112339 DOT QAA02273 AT dfw-ix8 DOT ix DOT netcom DOT com>
Reply-To:	fighteer AT cs DOT com
NNTP-Posting-Host:	ppp108.cs.com
Mime-Version:	1.0
To:	Alexey Kouzmitch <alexey AT ix DOT netcom DOT com>
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Alexey Kouzmitch wrote:
> 
>         I get a weird crash if I try something like:
> 
> _file_id1=fgetc(_lib_file);
> or,
> read (_lib_file,_file_id1);
> 
> where _libe_file is FILE* and _file_id is an int...
> 
> How do I got the best way about reading bytes (or structures) from files
> anyway ???
> 
> Thanks ahead! I'll be very grateful for HELP !!!
> 
>                                          Alexey Kouzmitch.

Umm... that doesn't look quite right.  Here's how I'd go about reading a
series of characters from a file - look at this to see what you're doing
different:

#include <stdio.h>

#define MAX 10000

int main( void )
{
    static char data[MAX];
    FILE *fp;
    int c, i;

    if ( ( fp = fopen( "foo.dat", "rb" ) ) == NULL )
    {
        perror( "foo.dat" );
        exit( 1 );
    }

    for ( i = 0; ( c = fgetc( fp ) ) != EOF && i < MAX; i++ )
        data[i] = (char) c;

    if ( i == MAX && c != EOF )
        printf( "Buffer overflow.\n" );

    fclose( fp );
    return 0;
}

As far as read() is concerned, you're using it wrong.  It takes three
parameters:  the file descriptor (an integer), a pointer to a buffer,
and a number of bytes to read.  You're trying to pass it a file pointer
and an integer, and there's no way that's going to work.  Anyway, if you
are going to use file pointers, you should be using fread() (which takes
a buffer, the size of each item, the number of items, and a file
pointer); here's a sample:

#include <stdio.h>

#define MAX 10000

int main( void )
{
    char data[MAX];
    FILE *fp;
    int r;

    if ( ( fp = fopen( "foo.dat", "rb" ) ) == NULL )
    {
        perror( "foo.dat" );
        exit( 1 );
    }

    r = fread( data, sizeof( *data ), MAX, fp );

    fclose( fp );
    return 0;
}

I seriously recommend that you look in the libc docs for fgetc(),
fread(), read(), etc., and find a good C book.  :)

-- 
John M. Aldrich <fighteer AT cs DOT com>                      

* Anything that happens, happens.
* Anything that, in happening, causes something else to happen,
  causes something else to happen.
* Anything that, in happening, causes itself to happen again, happens
  again.
* It doesn't necessarily do it in chronological order, though.
 
                                       --- Douglas Adams

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