Setting the File Pointer
Use the SetFilePointer function to move the file pointer a specified number of bytes. Like the ReadFile and WriteFile functions, SetFilePointer uses the handle that is returned by the CreateFile function in the hFile parameter to identify the file in which to move the pointer. The number of bytes that is described by the lDistanceToMove and lpDistanceToMoveHigh parameters can be relative to the beginning of the file or relative to the current position of the pointer. Specify the method to use in the dwMoveMethod parameter. If you pass in a positive number of bytes, SetFilePointer moves the file pointer toward the end of the file. If you pass in a negative number, SetFilePointer moves the file pointer toward the beginning of the file.