C# Signature:

[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
static extern uint GetLogicalDriveStrings(uint bufferLength, [Out] char[] buffer);
[DllImport("kernel32.dll")]
static extern uint GetLogicalDrives();

User-Defined Types:

None.

Parameters:

bufferLength, The maximum size of the buffer pointed to by buffer, in TCHARs. This size does not include the terminating null character. If this parameter is zero, buffer is not used.

buffer, A pointer to a buffer that receives a series of null-terminated strings, one for each valid drive in the system, plus with an additional null character. Each string is a device name.

Notes:

Returns a 32 bit value representing the availability of the drives of the computer.

If A: is present first bit is 1. If C: is present 3rd bit is 1. If not present zero is assigned.

Use GetDriveType to find the type of the drive.

DO NOT define using a StringBuilder, because only the first string would be returned.

[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
static extern uint GetLogicalDriveStrings(uint bufferLength, [Out] StringBuilder buffer);

Tips & Tricks:

Since arrays are reference types, we can pass an array of chars. Initialize your array prior to calling the function:

char[] buffer = new char[bufferLength];

Please add some!

Sample Code:

using System;
using System.Collections.Specialized;
using System.Runtime.InteropServices;

public class Mainline
{
    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    static extern uint GetLogicalDriveStrings(uint bufferLength, [Out] char[] buffer);

uint shift=1;

uint dr = GetLogicalDrives();

Console.WriteLine("Your drives are ...\n");

for(int i = 0; i<26 ; i++){

    if((shift & dr) == 1)
        Console.WriteLine("{0}:",(char)('a'+i));
    shift <<=1;

}

Alternative Managed API:

    public static void Main()
    {
       const int size = 512;
       char[] buffer = new char[size];
       uint code = GetLogicalDriveStrings(size, buffer);

       if (code == 0)
       {
      Console.WriteLine("Call failed");
      return;
       }

       StringCollection list = new StringCollection();
       int start = 0;
       for (int i = 0;  i < code;  ++i)
       {
      if (buffer[i] == 0)
      {
         string s = new string(buffer, start, i - start);
         list.Add(s);
         start = i + 1;
      }
       }

       foreach (string s in list)
      Console.WriteLine(s);
    }
}

Alternative Managed API:

public static string[] System.Environment.GetLogicalDrives();

public static System.IO.DriveInfo[] System.IO.DriveInfo.GetDrives();

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