More Pointer Woes

More Pointer Woes

[Joseph D. Wagner]

I get:

find.c:341: error: request for member `blocksize' in something not a 
structure or union

on line 341:

block_order_log.total_blocks = inode.i_blocks / ((fs->blocksize) / 512);

fs is a pointer but blocksize isn't.

This one's probably staring me in the face but I can't figure it out.  I 
need a fresh pair of eyes.

TIA guys (and gals) for all your support.

Joseph D. Wagner

Re: More Pointer Woes

[Joseph D. Wagner]

> "fs->blocksize" refers to a field "blocksize" in a struct or union that
> the pointer "fs" indicates.  If  "fs" isn't a pointer to a struct (or
> union) then the "->" operator isn't valid.  What type is "fs"?

ext2_filsys *fs which can be found in ext2fs.h

> P.S.  Did you get this code from an email? Perhaps the ">" came from an
> email quote that didn't get cleaned up and "fs-blocksize" morphed into
> "fs->blocksize".  But this looks like a long-shot to me.  I expect that
> "fs" is supposed to be a pointer to a struct.

No, I wrote it myself.  I've tried:

fs.blocksize
fs->blocksize
*(fs).blocksize (which should be the same thing)
*(fs->blocksize)
*fs->blocksize
*(fs.blocksize)
&(fs->blocksize)

To simplify it:

int blocksize_k = fs->blocksize;

also fails.  blocksize is of type int.

Joseph D. Wagner

Re: More Pointer Woes

[Jeff Woods]

At 12/28/2003 07:45 PM +0600, Joseph D. Wagner wrote:
>find.c:341: error: request for member `blocksize' in something not a 
>structure or union
>
>on line 341:
>
>block_order_log.total_blocks = inode.i_blocks / ((fs->blocksize) / 512);
>
>fs is a pointer but blocksize isn't.

"fs->blocksize" refers to a field "blocksize" in a struct or union that the 
pointer "fs" indicates.  If  "fs" isn't a pointer to a struct (or union) 
then the "->" operator isn't valid.  What type is "fs"?

P.S.  Did you get this code from an email? Perhaps the ">" came from an 
email quote that didn't get cleaned up and "fs-blocksize" morphed into 
"fs->blocksize".  But this looks like a long-shot to me.  I expect that 
"fs" is supposed to be a pointer to a struct.

--
Jeff Woods <kazrak+kernel@cesmail.net> 

RE: More Pointer Woes

[Mariano Moreyra]

The problem is that ext2_filsys is a pointer itself to a
struct struct_ext2_filsys
declaration in ext2fs.h:
typedef struct struct_ext2_filsys *ext2_filsys

so, you have a pointer to a pointer to a structure.
I think you should declare fs as an ext2_filsys type, like this:
ext2_filsys fs;
Then you could reference blocksize the way you are doing it in your
code...that is
fs->blocksize

Mariano Moreyra.


-----Mensaje original-----
De: linux-c-programming-owner@vger.kernel.org
[mailto:linux-c-programming-owner@vger.kernel.org]En nombre de Joseph D.
Wagner
Enviado el: Domingo, 28 de Diciembre de 2003 13:06
Para: Jeff Woods
CC: linux-c-programming@vger.kernel.org
Asunto: Re: More Pointer Woes


> "fs->blocksize" refers to a field "blocksize" in a struct or union that
> the pointer "fs" indicates.  If  "fs" isn't a pointer to a struct (or
> union) then the "->" operator isn't valid.  What type is "fs"?

ext2_filsys *fs which can be found in ext2fs.h

> P.S.  Did you get this code from an email? Perhaps the ">" came from an
> email quote that didn't get cleaned up and "fs-blocksize" morphed into
> "fs->blocksize".  But this looks like a long-shot to me.  I expect that
> "fs" is supposed to be a pointer to a struct.

No, I wrote it myself.  I've tried:

fs.blocksize
fs->blocksize
*(fs).blocksize (which should be the same thing)
*(fs->blocksize)
*fs->blocksize
*(fs.blocksize)
&(fs->blocksize)

To simplify it:

int blocksize_k = fs->blocksize;

also fails.  blocksize is of type int.

Joseph D. Wagner

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