From: "Damian Yerrick" <web DOT poison AT pineight DOT 8m DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: How to detect drives attached to a system
Date: Sun, 3 Oct 1999 23:04:12 -0500
Organization: Rose-Hulman Institute of Technology
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

IIRC, findfirst() and findnext() do not allow you to detect
what drive letters are valid and what drive letters are not
valid. This code, however, does.

/**************************************\
* DRIVES.C                             *
* Determine available drives           *
* For DJGPP                            *
* Copr. 1999 Damian Yerrick            *
\**************************************/

#include <stdio.h>
#include <stdlib.h>
#include <dos.h>
#include <direct.h>

int main(void)
{
  unsigned nDrives, curDrive, checkDrive;

  /* To determine the maximum number of drives available on this system */
  _dos_getdrive(&curDrive);
  printf("Current drive is %c:\n", curDrive + '@');
  _dos_setdrive(curDrive, &nDrives);
  puts("Drive letters installed:");

  for(checkDrive = 1; checkDrive <= nDrives; checkDrive++)
  {
    unsigned int pdrive;

/* in Borland, I used a command similar to if(_chdrive(checkDrive) == 0) */
    _dos_setdrive(checkDrive, &pdrive);
    _dos_getdrive(&pdrive);
    if(pdrive == checkDrive)
      printf("%c:, ", checkDrive + '@');
  }

  putchar('\n');
  _dos_setdrive(curDrive, &nDrives);

  return 0;
}

Can anyone see a problem with this code? It works on
Sindows 98's DOS box, but will it have problems under NT?
Is there a more portable way to detect all drives on a system?

--
Damian Yerrick
CM 398, Rose-Hulman Institute of Technology
5500 Wabash Ave
Terre Haute, IN 47803
http://come.to/yerrick