CFile::Seek

Repositions the file pointer in an open file.

virtual ULONGLONG Seek(
   LONGLONG lOff,
   UINT nFrom 
);

Parameters

• lOff
  Number of bytes to move the file pointer. Positive values move the file pointer towards the end of the file; negative values move the file pointer towards the start of the file.

• nFrom
  Position to seek from. See the Remarks section for possible values.

Return Value

The position of the file pointer if the method was successful; otherwise, the return value is undefined and a pointer to a CFileException exception is thrown.

Remarks

The following table lists possible values for the nFrom parameter.

Value	Description
CFile::begin	Seek from the start of the file.
CFile::current	Seek from the current location of the file pointer.
CFile::end	Seek from the end of the file.

When a file is opened, the file pointer is positioned at 0, the start of the file.

You can set the file pointer to a position beyond the end of a file. If you do this, the size of the file does not increase until you write to the file.

The exception handler for this method must delete the exception object after the exception is processed.

Example

CFile cfile;
cfile.Open(_T("Seek_File.dat"), CFile::modeCreate |
    CFile::modeReadWrite);
LONGLONG lOffset = 1000;
ULONGLONG lActual;
lActual = cfile.Seek(lOffset, CFile::begin);

Requirements

Header: afx.h

See Also

Reference

CFile Class

Hierarchy Chart

Other Resources

CFile Members

Change History

Date	History	Reason
October 2008	Updated whole topic.	Customer feedback.