C# Signature:

[DllImport("kernel32.dll")]
static extern bool SetFilePointerEx(IntPtr hFile, long liDistanceToMove,
   IntPtr lpNewFilePointer, uint dwMoveMethod);
    public enum EMoveMethod : uint
    {
        Begin = 0,
        Current = 1,
        End = 2
    }

C# Signature:

[DllImport("kernel32.dll")]
public static extern bool SetFilePointerEx(
     SafeFileHandle hFile, long liDistanceToMove,
     out long lpNewFilePointer, uint dwMoveMethod);
    [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    static extern unsafe uint SetFilePointer(
        [In] SafeFileHandle hFile,
        [In] int lDistanceToMove,
        [Out] int* lpDistanceToMoveHigh,
        [In] EMoveMethod dwMoveMethod);

    [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    static extern uint SetFilePointer(
        [In] SafeFileHandle hFile,
        [In] int lDistanceToMove,
        [Out] out int lpDistanceToMoveHigh,
        [In] EMoveMethod dwMoveMethod);

User-Defined Types:

None.

VB Signature:

    Public Enum EMoveMethod : uint
        FILE_BEGIN = 0
        FILE_CURRENT = 1
        FILE_END = 2
    End Enum

Notes:

None.

    <DllImport("kernel32.dll", SetLastError:=True)> _
    Shared Function SetFilePointer( _
        ByVal hFile As IntPtr, _
        ByVal lDistanceToMove As Integer, _
        ByRef lpDistanceToMoveHigh As IntPtr, _
        ByVal dwMoveMethod As EMoveMethod) _
        As System.UInt32
    End Function

Tips & Tricks:

The third argument (lpNewFilePointer) is of type LARGE_INTEGER, which has a size of 64 bits. For this reason use a UInt64 for this argument. (See sample below)

    Public Const INVALID_SET_FILE_POINTER As Integer = -1

Sample Code:

UInt64 n = 0; //it is important to use UInt64, because the 3rd argument is of type PLARGE_INTEGER, where LARGE_INTEGER has a size of 64 bits.

IntPtr ptr = new IntPtr(&n);

SetFilePointerEx(handle, 0, ptr, FILE_CURRENT);//ptr contains current location of file pointer. handle is a pointer to an open file handle.

Notes:

If you are using this function to access hard-disk sectors greater than (2^32 - 2) bytes,

then the third argument will not be null or IntPtr.Zero. So when you pass an IntPtr to

the third argument, pass it as a reference. To do this, just change the third argument signature

to: ref IntPtr lpDistanceToMoveHigh.

None.

Tips & Tricks:

Please add some!

Sample Code:

    [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    private static extern int SetFilePointer(IntPtr handle, int lDistanceToMove, out int lpDistanceToMoveHigh, uint dwMoveMethod);

Alternative Managed API:

Do you know one? Please contribute it!

    public long Seek(IntPtr handle, long offset, SeekOrigin origin)
    {
    uint moveMethod = 0;

LARGE_INTEGER - http://msdn.microsoft.com/en-us/library/aa383713(VS.85).aspx

UInt64 - http://msdn.microsoft.com/en-us/library/system.uint64.aspx

    switch (origin)
    {
        case SeekOrigin.Begin:
        moveMethod = 0;
        break;

        case SeekOrigin.Current:
        moveMethod = 1;
        break;

        case SeekOrigin.End:
        moveMethod = 2;
        break;
    }

    int lo = (int)(offset & 0xffffffff);
    int hi = (int)(offset >> 32);

    lo = SetFilePointer(handle, lo, out hi, moveMethod);

    if (lo == -1)
    {
        if (GetLastError() != 0)
        {
        throw new Exception("INVALID_SET_FILE_POINTER");
        }
    }

    return (((long)hi << 32) | (uint)lo);
    }

Alternative Managed API:

Do you know one? Please contribute it!

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