How to list and sort files in some directory by the names on Linux/Win in C ?

Xeratul · 10-03-2015, 01:45 AM

Hello,

How to list and sort files in some directory by the names on Linux/Win in C ?

The is a method using scandir, but I would be prefering to use readdir, DIR *mydirectory, ... !

Code:

#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>

int
main(void)
{
   struct dirent **namelist;
   int n;

   n = scandir(".", &namelist, 0, alphasort);
   if (n < 0)
       perror("scandir");
   else {
       while (n--) {
       printf("%s\n", namelist[n]->d_name);
       free(namelist[n]);
       }
       free(namelist);
   }
}

NevemTeve · 10-03-2015, 04:35 AM

unix: opendir/readdir/closedir
Windows: FindFirstFile/FindNextFile/FindClose
sort: qsort

Xeratul · 10-03-2015, 05:45 AM

Quote:

Originally Posted by NevemTeve

unix: opendir/readdir/closedir
Windows: FindFirstFile/FindNextFile/FindClose
sort: qsort

1) First, thank you for giving hints, however after long unsucessfull search, I would be please to get a simple example.

If you do not not, anyhow, thank you for giving some hints.

2) Secondly, I would advise to stick to the combination of "readdir" and "qsort", which is likely the most portable/compatible method for Win and Unix/BSD/*nix.

3) The real need of the user:
Would you have PLEASE a very simple basic minimal example (such as the one above)? please.

edit/ for your knowledge: "readdir" is fairly compatible under Windows as well.

ntubski · 10-03-2015, 09:22 AM

Last time we tried this you refused to post the code that allegedly produced the errors you reported. I see there hasn't been much progress since then.

NevemTeve · 10-03-2015, 01:14 PM

@OP: I've just google'd for 'readdir example' and I got 187000 results...

Xeratul · 10-03-2015, 04:09 PM

Quote:

Originally Posted by NevemTeve

@OP: I've just google'd for 'readdir example' and I got 187000 results...

try readdir and qsort together.

Did you get any single example?

- none.

NevemTeve · 10-04-2015, 04:01 AM

Try to implement this algorithm:

Code:

opendir
while (readdir successfull) {
    store data
}
closedir
sort data with qsort

Xeratul · 10-06-2015, 12:56 AM

Quote:

Originally Posted by NevemTeve

Try to implement this algorithm:

Code:

opendir
while (readdir successfull) {
    store data
}
closedir
sort data with qsort

Code:

#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>

int
main(void)
{
   char idata[250][250]; //for simplicity in this example
   int n=0;

   dirp = opendir(".");
   while ( (dp = readdir(dirp)) != NULL) {
        strncpy(idata[n++],dp->d_name, 250);    
    }
    closedir(dirp);
   

  // ok here, please help !!
  // thank you. 
}

NevemTeve · 10-06-2015, 02:57 AM

Code:

/* xeratul.c */

#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static int compare_fun (const void *p, const void *q);

int main (void)
{
   char idata[250][250]; //for simplicity in this example
   unsigned n=0;
   DIR *dirp;
   struct dirent *dp;

   dirp = opendir(".");
   while ((dp = readdir(dirp)) != NULL && 
	   n < sizeof idata / sizeof idata[0]) {
        strncpy(idata[n++],dp->d_name, 250);    
    }
    closedir(dirp);
   
    if (n>1)
	qsort (idata, n, sizeof idata[0], compare_fun);
}

static int compare_fun (const void *p, const void *q)
{
    const char *l= p;
    const char *r= q;
    int cmp;

    cmp= strcmp (l, r);
    return cmp;
}

Xeratul · 10-06-2015, 03:48 PM

Quote:

Originally Posted by NevemTeve

!!

Sincerely Thank You !!

+1! +10!!!