reading directly from C:\

irProject · December 7th, 2009, 03:21 AM

Hello
In C++ we can use fread function to read directly from C:\ drive. to do this we wrote following code
FILE *fp;
fp = fopen("C:","r+");
fread(...);

how to perform this by C#?

dparsons · December 7th, 2009, 03:03 PM

The following code will work assuming your code has privelages to read from the C drive (this will typically mean elevating the trust level of your code or running it as administrator):

csharp Code:

using System.IO;
using System.Text;
public class Foo
{
     public static void ReadFile()
     {
         using(TextReader reader = new StreamReader(@"C:\somefile.txt"))
         {
             StringBuilder data = new StringBuilder();
             data.Append(reader.ReadToEnd());
         }
     }
}

hth
-Doug

irProject · December 8th, 2009, 08:22 AM

I want to read directly sectors of drive C:

for example when i want to read from c:\someText.txt directly I could use this syntax:

fread("c:\\someText.txt\\","r+");

above command reads directly from hard disk (sector by sector)
how can i perform it by C# classes?

dparsons · December 8th, 2009, 09:36 AM

C# does not expose any native classes that will allow you to do this so you are going to need to use P/Inovke to call functions from the Win32 API's. This is the method you will probably want to invoke: http://www.pinvoke.net/default.aspx/kernel32.ReadFile

hth
-Doug

irProject · December 9th, 2009, 12:44 AM

Thanks a lot for your help.

irProject · December 14th, 2009, 04:19 AM

i found a sample code. that i will convert it into C#

Code:

Option Explicit


Private Type OVERLAPPED
    ternal As Long
    ternalHigh As Long
    offset As Long
    OffsetHigh As Long
    hEvent As Long
End Type


Public Declare Function CreateFile Lib "kernel32" Alias "CreateFileW" ( _
ByVal lpFileName As Long, _
ByVal dwDesiredAccess&, _
ByVal dwShareMode&, _
ByVal lpSecurityAttributes&, _
ByVal dwCreationDisposition&, _
ByVal dwFlagsAndAttributes&, _
ByVal hTemplateFile&) As Long

Public Declare Function ReadFile Lib "kernel32.dll" ( _
ByVal hFile As Long, _
ByRef lpBuffer As Any, _
ByVal nNumberOfBytesToRead As Long, _
ByRef lpNumberOfBytesRead As Long, _
ByRef lpOverlapped As OVERLAPPED) As Long


Public Declare Function CloseHandle Lib "kernel32" ( _
ByVal hObject&) As Long

Public Declare Function SetFilePointer Lib "kernel32" ( _
ByVal hFile As Long, _
ByVal lDistanceToMove As Long, _
lpDistanceToMoveHigh As Long, _
ByVal dwMoveMethod As Long) As Long

Public Declare Function GetFileSize Lib "kernel32" ( _
ByVal hFile As Long, _
lpFileSizeHigh As Long) As Long
 Public Const GENERIC_READ As Long = &H80000000
 Public Const GENERIC_WRITE As Long = &H40000000

 Public Const FILE_SHARE_READ As Long = &H1&
 Public Const FILE_SHARE_WRITE As Long = &H2&

 Public Const CREATE_NEW As Long = 1&
 Public Const CREATE_ALWAYS As Long = 2&
 Public Const OPEN_EXISTING As Long = 3&
 Public Const OPEN_ALWAYS As Long = 4&
 Public Const TRUNCATE_EXISTING As Long = 5&
 Public Const FILE_BEGIN As Long = 0

Public Function OpenTextFile(FileName As String) As String

Dim FileSize As Long
Dim hFile As Long
Dim lOverLapped As OVERLAPPED
Dim nReadRetVal As Long
Dim TxtBytes() As Byte
Dim Ret As Long
Dim  I As  Integer
Dim Start As Long

 hFile = CreateFile(StrPtr(FileName), GENERIC_READ, FILE_SHARE_READ, 0&, _
    OPEN_EXISTING, 0&, 0&)


If hFile = -1 Then ' Could Be An Error
    MsgBox "Error Opening File", vbCritical, "Error"
Else

FileSize = GetFileSize(hFile, 0) 'Get The Open File Size

 ReDim TxtBytes(FileSize) As Byte

 Start = 0 'Move The File Pointer
    Call SetFilePointer(hFile, Start, 0, FILE_BEGIN) ' Read The Whole File
    
    nReadRetVal = ReadFile(hFile, TxtBytes(0), UBound(TxtBytes), Ret, lOverLapped)
     If nReadRetVal = 0 Then
        MsgBox ("Error reading from file")
    Else
   For  I = LBound(TxtBytes) To UBound(TxtBytes) 'From 0 To The Len Of the File

  OpenTextFile = OpenTextFile & Chr(TxtBytes(i))
        Next

    End  If
End  If
CloseHandle hFile

End Function

irProject · December 14th, 2009, 04:23 AM

i will send C# sample code here. I have written this sample in C# but i have not tested that does it answer to read directly from drive.
i will notice you.