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이 문서에서는 PHP 중국어 웹사이트 매뉴얼 풀어 주다
(PHP 4 >= 4.2.0, PHP 5 <= 5.0.5, PHP 7)
dio_seek — Seeks to pos on fd from whence
$fd
, int $pos
[, int $whence
= SEEK_SET
] )The 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.
Example #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 );
?>