FSeek Function

Set the file pointer to a new position.

Namespace: XSharp.RT
Assembly: XSharp.RT (in XSharp.RT.dll) Version: 2.19

Syntax

 FUNCTION FSeek(
	ptrHandle,
	nOffset,
	kOrigin
) AS LONG CLIPPER

[ClipperCallingConventionAttribute(new string[] { ... })]
public static int FSeek(
	Usual ptrHandle = default,
	Usual nOffset = default,
	Usual kOrigin = default
)

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Parameters

ptrHandle (Optional)

Type: Usual
The handle of the open file.

nOffset (Optional)

Type: Usual
The number of bytes to move the file pointer, from the position defined by nOrigin.
It can be a positive or negative number.
A positive number moves the pointer forward in the file, and a negative number moves the pointer backward.
If nOrigin is the end-of-file, nOffset must be 0 or negative.

kOrigin (Optional)

Type: Usual
One of the following constants indicating the starting location of the file pointer, telling where to start searching the file:

Constant	Seeks from
FS_END	End-of-file
FS_RELATIVE	Current pointer position
FS_SET	Beginning-of-file

Return Value

Type: Long
The new position of the file pointer, relative to the beginning of the file (position 0). (The original position of the file pointer does not matter.)

Remarks

FSeek() is a low-level file function that moves the file pointer forward or backward in an open file without actually reading the contents of the specified file.
The file pointer cannot be moved beyond the beginning or end-of-file boundaries.

Remarks

Tip
This function is included for compatibility. We do not recomment using static memory for file i/o operations. We recommend that you use the function overload that takes a byte array parameter in stead.

Examples

This example uses FSeek() to determine the length of a file by seeking from the end-of-file.
Then, the file pointer is reset to the beginning-of-file:

Copy

 1// Open the file read-only
 2IF (ptrHandle := FOpen2("temp.txt", FO_READ)) != F_ERROR
 3    // Get length of the file
 4    nLength := FSeek(ptrHandle, 0, FS_END)
 5    // Reset file position to beginning-of-file
 6    FSeek(ptrHandle, 0)
 7    FClose(ptrHandle)
 8ELSE
 9    ? DOSErrString(FError())
10ENDIF

This example positions the file pointer at the last byte in a file:

Copy

1FUNCTION FileBottom(ptrHandle) AS LONGINT
2    RETURN (FSeek(ptrHandle, 0, FS_END))

This example positions the file pointer at the first byte in a file (same as the Rewind() function):

Copy

1FUNCTION FileTop(ptrHandle) AS LONGINT
2    RETURN (FSeek(ptrHandle, 0))

Reference

Functions, Globals and Defines

FReadStr(IntPtr, DWord)

FRewind(IntPtr)

FSeek3(IntPtr, Long, DWord)

FTell(IntPtr)

FWriteLine(Usual, Usual, Usual)