C# Signature:
[DllImport("kernel32.dll")]
static extern uint GetCompressedFileSize(string lpFileName,
out uint lpFileSizeHigh);
VB .NET Signature:
Private Declare Function GetCompressedFileSize Lib "kernel32" Alias "GetCompressedFileSizeA" (ByVal lpFileName As String, ByVal lpFileSizeHigh As IntPtr) As UInt32
Legacy VB Signature:
Private Declare Function GetCompressedFileSize Lib "kernel32" Alias "GetCompressedFileSizeA" (ByVal lpFileName As String, lpFileSizeHigh As Long) As Long
User-Defined Types:
None.
Notes:
The code below correctly obtains the compressed file size also if above 4GB. (Fixed VB and C# code, 2012 Eske Rahn)
Tips & Tricks:
Please add some!
Sample Code C#:
[DllImport("kernel32.dll", SetLastError=true, EntryPoint="GetCompressedFileSize")]
static extern uint GetCompressedFileSizeAPI(string lpFileName, out uint lpFileSizeHigh);
public ulong GetCompressedFileSize(string filename)
{
uint high;
uint low;
low = GetCompressedFileSizeAPI(filename, out high);
int error = Marshal.GetLastWin32Error();
if (low == 0xFFFFFFFF && error != 0)
throw new Win32Exception(error);
else
return ((ulong)high << 32) + low;
}
Sample Code VB .NET:
Imports System.IO
·
·
·
Public Function CompressedFileSize(ByVal path As String) As Long
If File.Exist(path) Then
Try
' Return Convert.ToInt64(GetCompressedFileSize(path, IntPtr.Zero))
' To handle 4Gb+ a bit more complex:
Dim ptr As IntPtr = Marshal.AllocHGlobal(4)
Try
Dim filelength as Long = Convert.ToInt64(GetCompressedFileSize(path, ptr))
If filelength = &HFFFFFFFF Then
Dim Err As Long = Marshal.GetLastWin32Error()
If Err <> 0 Then Throw New IOException("Exception getting compressed size: " & Err.ToString)
End If
Return filelength + CLng(Marshal.ReadInt32(ptr)) << 32
Finally
Marshal.FreeHGlobal(ptr)
End Try
Catch ex As Exception
Throw New IOException("The compressed size of the specified file could not be determined.")
End Try
End If
End Function
Sample code legacy VB:
Private Sub GetFileSize(ByVal strPath As String)
MsgBox "The size of " + strPath " is " + CStr(GetCompressedFileSize(strPath, ByVal 0&)) + " bytes "
End Sub
Alternative Managed API:
The ManagedWindowsApi project (http://mwinapi.sourceforge.net) provides an ExtendedFileInfo class that contains utility methods for file information.
