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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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

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