C# Signature:

[DllImport("kernel32.dll", SetLastError=true, CharSet=CharSet.Auto)]
static extern uint GetWindowsDirectory(StringBuilder lpBuffer,
   uint uSize);

VB.NET Signature

<DllImport("kernel32.dll", SetLastError:=true, EntryPoint:="GetWindowsDirectoryW", CharSet:=CharSet.Unicode)> _
Public Function GetWindowsDirectory(<MarshalAs(UnmanagedType.LPTSTR)>lpBuffer As System.Text.StringBuilder, _
                   uSize As UInteger ) As UInteger
End function

VB Signature

Declare Function GetWindowsDirectory Lib "kernel32" Alias "GetWindowsDirectoryA" _
   (ByVal Buffer As String, ByVal Size As Integer) As Integer

User-Defined Types:

None.

Notes:

Q. For the above VB DllImport declaration, Visual Studio's Code Analysis throws error 'CA2101: Specify marshaling for P/Invoke string arguments'.

Should the marshalling not be: <MarshalAs(UnmanagedType.LPWStr)> Otherwise lpBuffer will be converted to Ansi and then passed to a Unicode API method.

Q. For the above VB DllImport declaration, Visual Studio Code Analysis throws error 'CA2101: Specify marshaling for P/Invoke string arguments'. Should the marshalling not be: <MarshalAs(UnmanagedType.LPWStr)> ?

Otherwise lpBuffer will be converted to Ansi and then passed to a Unicode API method.

Tips & Tricks:

Please add some!

Here are two ways to get the Windows path

   Private Sub test()
      Dim sSystemPath As String = System.Environment.GetFolderPath(Environment.SpecialFolder.System)
      MessageBox.Show(sSystemPath.Substring(0, sSystemPath.LastIndexOf("\")))
      MessageBox.Show(System.Environment.GetEnvironmentVariable("windir"))
   End Sub

VB Sample Code:

   As SDim WinDir tring = Space(255)
   Dim Res As Integer = GetWindowsDirectory(WinDir, WinDir.Length)
   WinDir = WinDir.Substring(0, Res)

VB.NET Sample Code:

Shared Function wins() As String
     Dim sb As StringBuilder =new StringBuilder(100)
     Dim f as UInteger = 100
     GetWindowsDirectory(sb,i)
     return sb.ToString()  
End Function

C# Sample Code:

   const int MaxPathLength = 255;
   StringBuilder sb = new StringBuilder(MaxPathLength);
   int len = (int)GetWindowsDirectory(sb, MaxPathLength);
   _windowsDirectory = sb.ToString(0, len);

C# Sample Code (Alternative):

static string wins()
{
     StringBuilder sb =new StringBuilder(100);
     int i = 100; uint f;
     GetWindowsDirectory(sb,ref  i);
     return sb.ToString()  ;
}

Alternative Managed API:

Environment.GetEnvironmentVariable("windir");

Please edit this page!

Do you have...

• helpful tips or sample code to share for using this API in managed code?
• corrections to the existing content?
• variations of the signature you want to share?
• additional languages you want to include?

Select "Edit This Page" on the right hand toolbar and edit it! Or add new pages containing supporting types needed for this API (structures, delegates, and more).