How to Copy filenames in to array?

[Bertram]

Hi all

I read filenames present in folder with:

DIR *dir;
struct dirent *ent;

if ((dir = opendir ("C:\\")) != NULL) {
while ((ent = readdir (dir)) != NULL) {
printf ("%s\n", ent->d_name);
}
closedir (dir);

But how do copy filenames in char array?

char *namefilesinfolder[100];

strcpy(namefilesinfolder,ent->d_name); // don't work.

Thanks

Regards

[Francis Glassborow]

On 22/04/2013 12:55, Bertram wrote:
> Hi all
>
> I read filenames present in folder with:
>
> DIR *dir;
> struct dirent *ent;
>
> if ((dir = opendir ("C:\\")) != NULL) {
> while ((ent = readdir (dir)) != NULL) {
> printf ("%s\n", ent->d_name);
> }
> closedir (dir);
>
> But how do copy filenames in char array?
>
> char *namefilesinfolder[100];

That declares an array of 100 pointers to char. I doubt that is what you
intended.

Omit the asterisk and one source of error goes, I cannot comment on the
rest as you are using a POSIX extension to C.

[Keith Thompson]

Francis Glassborow <francis.g...@btinternet.com> writes:
> On 22/04/2013 12:55, Bertram wrote:
>> I read filenames present in folder with:
>>
>> DIR *dir;
>> struct dirent *ent;
>>
>> if ((dir = opendir ("C:\\")) != NULL) {
>> while ((ent = readdir (dir)) != NULL) {
>> printf ("%s\n", ent->d_name);
>> }
>> closedir (dir);
>>
>> But how do copy filenames in char array?
>>
>> char *namefilesinfolder[100];
>
> That declares an array of 100 pointers to char. I doubt that is what you
> intended.

Since he's reading multiple file names, I suspect it is what he intended.

> Omit the asterisk and one source of error goes, I cannot comment on the
> rest as you are using a POSIX extension to C.
>>
>> strcpy(namefilesinfolder,ent->d_name); // don't work.

ent->d_name gives you a pointer to a string containing a file name. You
call it repeatedly, so you'll get multiple strings.

You have an array of pointers to char. You can make each char* element
of that array point to a string. But you have to allocate space for the
string.

You can't just assign the pointer value of ent->d_name to successive
elements of namefilesinfolder, because each call to readdir() can
clobber the memory used by the previous call; you have to allocate space
for each string and copy the string itself.

In the body of your loop, you could write something like:

namefilesinfolder[index] = malloc(strlen(ent->d_name) + 1);
if (namefilesinfolder[index]) {
/* malloc failed, handle error somehow; do *not* just keep going */
}
strcpy(namefilesinfolder[index], ent->d_name);
index ++;

This is similar to what the non-standard strdup() function does
(non-standard in the sense that it's defined by POSIX but not by
the C standard).

I've ignored the possibility that there are more than 100 files in
the directory. You shouldn't.

--
Keith Thompson (The_Other_Keith) ks...@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

[Bertram]

Ok, thanks.

Regards