scandir and file_select()

[Sheldon]

Hi,

I have a little warning that I am trying to understand but it escapes
me. Perhaps someone can help here.
I have the function read_files() that scans the directory and return
the desired file names after filtering.
I have used the function file_select() to filter out unwanted files
and everything works nicely except that I keep getting the warning:

"warning: passing argument 3 of 'scandir' from incompatible pointer
type"

********

int read_files() {
/* Read directory and find desired files */
/* file_select is used to sort the files and fetch the desired files
*/
return scandir(DIR, &list, file_select, alphasort);
}

int file_select(struct direct *entry) {
if (strstr(entry->d_name,FILTER1) && strstr(entry->d_name,FILTER2)
&& strstr(entry->d_name,FILTER3)) {
return TRUE;
} else {
return FALSE;
}
}
Can someone enlighten me please!

/S

[Richard Heathfield]

Sheldon said:

Hi,

I have a little warning that I am trying to understand but it escapes
me. Perhaps someone can help here.
I have the function read_files() that scans the directory and return
the desired file names after filtering.
I have used the function file_select() to filter out unwanted files
and everything works nicely except that I keep getting the warning:

"warning: passing argument 3 of 'scandir' from incompatible pointer
type"

Then you're passing the wrong kind of argument to scandir.

In comp.os.linux.development.apps or possibly comp.unix.programmer, I would
imagine that they'd be able to tell you exactly which kind of argument
you're supposed to pass.

<OT>
In BSD4.3, scandir takes int(*)(const struct dirent **, const struct dirent
**) as its third argument, whereas alphasort has the prototype int(const
void *, const void *).
</OT>

<snip>

--
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

[Jens Thoms Toerring]

Sheldon <sh******@gmail.comwrote:

Hi,

I have a little warning that I am trying to understand but it escapes
me. Perhaps someone can help here.
I have the function read_files() that scans the directory and return
the desired file names after filtering.
I have used the function file_select() to filter out unwanted files
and everything works nicely except that I keep getting the warning:

"warning: passing argument 3 of 'scandir' from incompatible pointer
type"

********

int read_files() {
/* Read directory and find desired files */
/* file_select is used to sort the files and fetch the desired files
*/
return scandir(DIR, &list, file_select, alphasort);
}

int file_select(struct direct *entry) {
if (strstr(entry->d_name,FILTER1) && strstr(entry->d_name,FILTER2)
&& strstr(entry->d_name,FILTER3)) {
return TRUE;
} else {
return FALSE;
}
}

Can someone enlighten me please!

scandir() isn't a C standard function so you should instead ask in
comp.unix.programmer (I guess that's what you're using, at least
there is a scandir() function in UNIX that looks familiar to me, if
that guess is wrong look for a group dealing with your sytem). So
here's just an (off-topic) hint: under UNIX the file_select() func-
tion is supposed to take a const struct dirent pointer as its argu-
ment, note the const qualifier and the difference between the words
'direct' and 'dirent'.
Regards, Jens
--
\ Jens Thoms Toerring ___ [e-mail]
\__________________________ http://toerring.de

[Sheldon]

On 20 Aug, 14:33, [e-mail] (Jens Thoms Toerring) wrote:

Sheldon <[e-mail]:

Hi,
I have a little warning that I am trying to understand but it escapes
me. Perhaps someone can help here.
I have the function read_files() that scans the directory and return
the desired file names after filtering.
I have used the function file_select() to filter out unwanted files
and everything works nicely except that I keep getting the warning:
"warning: passing argument 3 of 'scandir' from incompatible pointer
type"
********
int read_files() {
/* Read directory and find desired files */
/* file_select is used to sort the files and fetch the desired files
*/
return scandir(DIR, &list, file_select, alphasort);
}
int file_select(struct direct *entry) {
if (strstr(entry->d_name,FILTER1) && strstr(entry->d_name,FILTER2)
&& strstr(entry->d_name,FILTER3)) {
return TRUE;
} else {
return FALSE;
}
}
Can someone enlighten me please!

scandir() isn't a C standard function so you should instead ask in
comp.unix.programmer (I guess that's what you're using, at least
there is a scandir() function in UNIX that looks familiar to me, if
that guess is wrong look for a group dealing with your sytem). So
here's just an (off-topic) hint: under UNIX the file_select() func-
tion is supposed to take a const struct dirent pointer as its argu-
ment, note the const qualifier and the difference between the words
'direct' and 'dirent'.
Regards, Jens
--
\ Jens Thoms Toerring ___ [e-mail]
\__________________________ http://toerring.de

Thanks guys! I'll go on to the linux group.

/S

[viza]

On Wed, 20 Aug 2008 12:30:15 +0000, Richard Heathfield wrote:

Sheldon said:

>"warning: passing argument 3 of 'scandir' from incompatible pointer
type"

Then you're passing the wrong kind of argument to scandir.

In BSD4.3, scandir takes int(*)(const struct dirent **, const struct
dirent **) as its third

fourth

argument, whereas alphasort has the prototype
int(const void *, const void *).

[viza]

On Wed, 20 Aug 2008 05:03:18 -0700, Sheldon wrote:

Add:

int file_select(struct direct *entry);

before

int read_files() {

[Richard Heathfield]

viza said:

On Wed, 20 Aug 2008 12:30:15 +0000, Richard Heathfield wrote:

>Sheldon said:

>>"warning: passing argument 3 of 'scandir' from incompatible pointer
type"

Then you're passing the wrong kind of argument to scandir.

In BSD4.3, scandir takes int(*)(const struct dirent **, const struct
dirent **) as its third

fourth

Oh yes. Thank you. Well, in that case he actually got (at least!) two args
wrong.

--
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

[Keith Thompson]

viza <to******@gm-il.com.obviouschange.invalidwrites:

On Wed, 20 Aug 2008 05:03:18 -0700, Sheldon wrote:

Add:

int file_select(struct direct *entry);

before

int read_files() {

Yes, that could be part of the problem. In the code fragment Sheldon
posted, there's no visible prototype for file_select at the point
where its name is used in the call to scandir. In C90 mode, the
compiler will assume that a function with no visible declaration
returns int. (C99 dropped implicit int.)

Also, read_files is declared with no prototype:

int read_files() { ... }

This is legal, but rarely a good idea. If it takes no arguments,
say so:

int read_files(void) { ... }

--
Keith Thompson (The_Other_Keith) ks***@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"