How to get name of files in local directory using C++

tnjones · 08-13-2008, 07:42 PM

Hello,
I am new to Linux and am trying to write a program in C++ for Linux that will concatenate all files in the ./ directory (i.e. local) directory in alphabetical order. I have searched on the web and haven't really found anything that I fully understand. I will greatly appreciate any advice!!!

CRC123 · 08-13-2008, 08:54 PM

Found this for you. However, I don't know how to figure out the current directory and my Linux Programming book is at work. I remember seeing it in the book, but I'll look tomorrow.

tnjones · 08-13-2008, 09:10 PM

Thanks! I will look up the info you provided!

CRC123 · 08-14-2008, 10:54 AM

Got to my book and found how to get current directory:

Code:

#include <unistd.h>
char *getcwd(char *buf, size_t size);

lol, so easy but so hard to remember

Here's a good overview of how it works.

Good Luck

ta0kira · 08-14-2008, 02:36 PM

I believe scandir would be more appropriate. I find it works very well, especially since you can filter and/or sort the entries before the list is complete.
ta0kira

matthewg42 · 08-14-2008, 03:48 PM

The usual ways to access directory contents on *nix systems is to use opendir/readdir/close dir or glob. See the manual pages for these commands for more info.

Sorting would likely be a separate activity. You might as well use the STL classes and functions for this.

ta0kira · 08-14-2008, 05:39 PM

Quote:

Originally Posted by matthewg42

Sorting would likely be a separate activity. You might as well use the STL classes and functions for this.

Or do it all in C with one function call:

Code:

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

int main()
{
    struct dirent **entries = NULL, **current = NULL;

    if (scandir(".", &entries, NULL, &alphasort) != -1)
    {
    if ((current = entries))
    while (*current)
    fprintf(stderr, "%s\n", (*current++)->d_name);
    }

    free(entries);

    return 0;
}

ta0kira

PS If alphasort isn't available on your system, it's pretty simple to create your own:

Code:

#include <string.h>

static int alphasort2(const void *a, const void *b)
{ return strcmp( (*(struct dirent**) a)->d_name, (*(struct dirent**) b)->d_name ); }

tnjones · 08-14-2008, 10:24 PM

Thanks!! This is sooo helpful!!