argument 3 confusion in scandir()

Hi,

this might be an easy question: I want to use scandir()

Code:

int scandir(const char *dir, struct dirent ***namelist, int(*filter)(const struct dirent *), int(*compar)(const struct dirent **, const struct dirent **));

My program simply reads the entries in ".". I know how to get it run when my file_select
function comes after main() and in main there's

Code:

int file_select();

declared.

Code:

#include <sys/dir.h>
#include <stdio.h>
#include <stdlib.h> //exit()
#include <string.h> //strcmp()
 
extern  int alphasort();

int main()
{
   int file_select();

   int count,i;
   struct dirent **files;
   
   count = scandir(".", &files, file_select, alphasort);
  //count = scandir(".", &files, &file_select, alphasort);
   if (count <= 0){
     printf("No files in this directory\n");
     exit(0);
   }
 
   printf("Number of files = &#37;d\n",count);
   for (i=1;i<count+1;++i)
     printf("%s\n",files[i-1]->d_name);
     return 0;
}
int file_select(struct dirent *entry)
{
   if ((strcmp(entry->d_name, ".") == 0) || (strcmp(entry->d_name, "..") == 0))
     return (0);
   else
     return (1);
}

My first question is:
So why is there no difference if I call scandir() with &file_select or just file_select?

My second issue is:
But I want that the function file_select comes before the main. Then I run into a warning:

warning: passing argument 3 of ‘scandir’ from incompatible pointer type

Ok, I tried it with
count = scandir(".", &files, &file_select, alphasort);
and
count = scandir(".", &files, file_select, alphasort);

and also with this
int file_select() declaration in main() and without...

but it just doesnt work. I guess it has something to do with pointer and implicit declarations. However I have no idea what s the difference.

Thanks TurboToJo

> int(*filter)(const struct dirent *)
Which means your function prototype should look like this
int file_select ( const struct dirent *d );
to match the definition which follows.

The same goes for the compare function.

Also, you don't need the & in C to indicate that a function name is a function pointer.

ok thanks,

so then there was just the const missing. ARGH

thanks for pointing that out
TurboToJo