PHP - Manual: dio_seek
2024-11-13
(PHP 4 >= 4.2.0, PHP 5 < 5.1.0)
dio_seek — Seeks to pos on fd from whence
$fd
, int $pos
, int $whence
= SEEK_SET): intThe function dio_seek() is used to change the file position of the given file descriptor.
fd
The file descriptor returned by dio_open().
pos
The new position.
whence
Specifies how the position pos
should be
interpreted:
SEEK_SET
(default) - specifies that
pos
is specified from the beginning of the
file.
SEEK_CUR
- Specifies that
pos
is a count of characters from the current
file position. This count may be positive or negative.
SEEK_END
- Specifies that
pos
is a count of characters from the end of
the file. A negative count specifies a position within the current
extent of the file; a positive count specifies a position past the
current end. If you set the position past the current end, and
actually write data, you will extend the file with zeros up to that
position.
示例 #1 Positioning in a file
<?php
$fd = dio_open('/dev/ttyS0', O_RDWR);
dio_seek($fd, 10, SEEK_SET);
// position is now at 10 characters from the start of the file
dio_seek($fd, -2, SEEK_CUR);
// position is now at 8 characters from the start of the file
dio_seek($fd, -5, SEEK_END);
// position is now at 5 characters from the end of the file
dio_seek($fd, 10, SEEK_END);
// position is now at 10 characters past the end of the file.
// The 10 characters between the end of the file and the current
// position are filled with zeros.
dio_close($fd);
?>