How to hide . and .. folders in C?

Question

I'm trying to list all folders and all files of a folder with the language C.

This is the following code:

#include <errno.h>
#include <stdio.h>
#include <dirent.h>
#include <sys/stat.h>

int main (int argc, char *argv[])
{
    struct dirent *direnp;
    struct stat filestat;
    DIR *dirp;

    if (argc != 2) {
        printf("error");
        return 1;
    }

    if ((dirp = opendir(argv[1])) == NULL) {
        printf("error");
        return 1;
    }

    while ((direnp = readdir(dirp)) != NULL)
    {
        stat(direnp->d_name, &filestat);
        printf("%s\n", direnp->d_name); 
    }

    return 0;
}

After entering the cmd ./file.c folder

The output from this code is:

folder1
folder2
file1.txt
..
.
file2.txt

I wish to remove this part:

..
.

So the output I wish is:

folder1
folder2
file1.txt
file2.txt

How do I hide the 3 dots?

(Edit: There were some mistakes in the code. I corrected it)

AFAIK the only way to do this is manually compare each entry's name with the strings "." and ".." and skip if they match — Drew McGowen, Feb 01 '14 at 20:13
@chux well the positions of ".." and "." are random. this is why i want to hide them. In my case, they were at 4th and 5th for me. — Lord Rixuel, Feb 01 '14 at 23:09
In some _poor_ code, code have taken advantage that the first 2 entries are often "." and ".." and simply skipped the first 2 entries. Good you are not doing the same. Note: a folder might not have a ".". — chux - Reinstate Monica, Feb 01 '14 at 23:16
@chux Just out of curiosity: Can you please direct me where to read more on folders not having a `.`? — Palec, Feb 03 '14 at 04:28
@Palec Fat finger mistake on my part. I should have said: Note: a folder might not have a "..". e.g. a top-level folder — chux - Reinstate Monica, Feb 03 '14 at 04:30
@chux That explains it. BTW POSIX forbids this. Base Definitions §4.12 Path Resolution says `The special filename dot-dot shall refer to the parent directory of its predecessor directory. As a special case, in the root directory, dot-dot may refer to the root directory itself.` and Rationale §4.12 says `Each directory has exactly one parent directory which is represented by the name dot-dot in the first directory. No other directory … is considered the parent directory by POSIX.1-2008.` and `What the filename dot-dot refers to relative to the root directory is implementation-defined.`. — Palec, Feb 03 '14 at 05:48

Andreas Fester · Accepted Answer · 2014-02-01T21:00:13.050

6

Simply filter them in your while loop:

if (strcmp(direnp->d_name, ".") != 0 && strcmp(direnp->d_name, "..") != 0) {
   printf("%s\n", direnp->d_name);    
}

edited Feb 01 '14 at 21:00

answered Feb 01 '14 at 20:14

Andreas Fester

36,091
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IMO the correct way would be to use the library functions( dirent.h ) to determine if the file is not a file or directory. – this Feb 01 '14 at 20:17
3

OP wants to list files **and** directories, but not the two special ones - afaik "." and ".." **are** normal directories (not pipes, not device files) – Andreas Fester Feb 01 '14 at 20:19
I said to determine if **not a file or directory** == anything else but a file or dir. So you can filter them. – this Feb 01 '14 at 20:21
1

@self But how would that allow to distinguish "." and ".."? – Andreas Fester Feb 01 '14 at 20:21
Read the library dirent.h. and look at types. – this Feb 01 '14 at 20:22
So, what do you think `type` will be for "." and ".."? – Andreas Fester Feb 01 '14 at 20:24
The code works correctly. Thank you Mr. Andreas. Just a little note, I forgot to type correctly d_name and the dirent name. Otherwise, everything works fine. – Lord Rixuel Feb 01 '14 at 20:52
@LordRixuel Yes, I recognized the same when I compiled your code, but then you already fixed it in the question - I also adjusted my answer now to match your code. Hint: ideally post exactly the code which you run through your compiler - simply do a copy&paste from your code editor – Andreas Fester Feb 01 '14 at 21:01

How to hide . and .. folders in C?

1 Answers1