List files in current directory

  • Thread starter Thread starter Kristan
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Kristan

Hi there, quick question, how would I retrieve a list of files in ANSI C in
a purely platform independent way?

Any pointers would be great!

thanks
Kristan
 
Kristan said:
Hi there, quick question, how would I retrieve a list of files in ANSI C in
a purely platform independent way?

Any pointers would be great!
Click to expand...
(I'm posting after reading on comp.lang.c. I don't know if it's suited to
the other NG's you posted to and you didn't set followups to the NG you are
reading from. Since, I don't know from which NG you are reading replies,
all NG's you posted to whether appropriate or not get this message.)

"in ANSI C"
- You don't. You could use POSIX C routines.
"in a purely platform independent way"
- You might use a platform specific version of Doug Gwyn's Public Domain
libndir package or create a multiplatform version from the various versions.
for BSD, libndir.tar.Z http://ftp.br.xemacs.org/pub/unix-c/languages/c/
for POSIX, libndir-posix.tar.Z
http://ftp.br.xemacs.org/pub/unix-c/languages/c/
for DOS, (several versions exist, I'm not looking them up unless you
_actually_ need them, i.e., beg)
- You might look at how multi-platform applications which store directory
structures work, like Info-ZIP, PDTar (Public Domain tar), GNU tar, etc...
Infozip http://www.info-zip.org/pub/infozip/
pdtar.tar.Z http://ftp.br.xemacs.org/pub/unix-c/tapes/

Programs like Info-ZIP and PDTar have to create their routines which perform
directory access identically on many platforms. However, those routines may
not be integrated into a single file...


Rod Pemberton
 
Hi there, well, POSIX sounds promising, as it seems to be supported on Linux
and Windows (2000 upwards), basically I'm using Windows for development and
the Debian Linux server is the platform.

Do you know whether POSIX is available with my Visual Studio 2005 C
compiler? Or would I have to obtain it separately?

thanks
Kristan
 
Kristan said:
Hi there, well, POSIX sounds promising, as it seems to be supported on Linux
and Windows (2000 upwards), basically I'm using Windows for development and
the Debian Linux server is the platform.

Do you know whether POSIX is available with my Visual Studio 2005 C
compiler? Or would I have to obtain it separately?
Click to expand...

I don't think it's directly supported. There is a POSIX subsystem for
Windows that you can download, but it does not use the Visual Studio C
compiler.

My approach when dealing with platform-specifics is to abstract the
functionality into functions that are conditionally compiled on each system.

Below is a directory lister for Windows, Unix/POSIX and MS-DOS.

#include <stdio.h>

#ifdef _WIN32

/* Compiling for Windows */

#include <windows.h>

int main(void)
{
WIN32_FIND_DATA f;
HANDLE h = FindFirstFile("./*", &f);
if(h != INVALID_HANDLE_VALUE)
{
do
{
puts(f.cFileName);
} while(FindNextFile(h, &f));
}
else
{
fprintf(stderr, "Error opening directory\n");
}
return 0;
}

#else
#ifdef __unix__

/* Compiling for UNIX / POSIX */

#include <sys/types.h>
#include <dirent.h>

int main(void)
{
DIR *dir = opendir(".");
if(dir)
{
struct dirent *ent;
while((ent = readdir(dir)) != NULL)
{
puts(ent->d_name);
}
}
else
{
fprintf(stderr, "Error opening directory\n");
}
return 0;
}

#else
#ifdef __TURBOC__

/* Compiling for MS-DOS */

#include <dir.h>

int main(void)
{
struct ffblk ffblk;
if(findfirst("*.*", &ffblk, 0) == 0)
{
do
{
puts(ffblk.ff_name);
} while(findnext(&ffblk) == 0);
}
else
{
fprintf(stderr, "Error opening directory\n");
}
return 0;
}

#else
#error Unsupported Implementation
#endif
#endif
#endif
 
Hi there, quick question, how would I retrieve a list of files in ANSI C in
a purely platform independent way?
Click to expand...

1. Prompt the user for the file names, one at a time.
2. Get the list of file names from argv[].
3. Open a file containing a list of file names and read it, one line at a time.
 
Kristan said:
Hi there, quick question, how would I retrieve a list of files in ANSI C in
a purely platform independent way?

Any pointers would be great!

thanks
Kristan
Click to expand...
Windows:
system("dir /b > file.lst");
Linux:
system("ls > file.lst");

might do it.
 
Joe Wright said:
Windows:
system("dir /b > file.lst");
Linux:
system("ls > file.lst");

might do it.
Click to expand...

Or it might not.

<OT>
In both cases, the command applies only to the current directory,
whatever that happens to be. The Unix command skips any files whose
names start with '.'. The order in which the files are listed may or
may not depend on the current locale. Either command will fail if you
don't have write permission in the current directory. If "file.lst"
already exists, the command will either clobber it or fail; if it
doesn't exist, you've just added a new file that may or may not show
up in the listing.
</OT>

Since you've provided different solutions for Windows and Linux, it's
obviously not "purely platform independent", which is what the OP was
asking for. The fact that you're using the standard function system()
doesn't make the code platform independent; it merely delays any
failure until execution time.

There is no purely platform independent solution.

Both Windows and Linux provide system-specific mechanisms for
retrieving a list of files (the Linux solution should work on any
Unix-like system). These mechanisms are far more flexible, and they
don't depend on creating and reading a temporary file in the very
directory you're trying to examine

This is one of those cases where trying to write portable code is a
waste of time; the non-portable solutions work better, and the
seemingly portable solution isn't portable at all.
 
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