dio_seek
(PHP 4 >= 4.2.0, PHP 5 <= 5.0.5)
dio_seek — Seeks to pos on fd from whence
说明
The function dio_seek() is used to change the file position of the given file descriptor.
参数
- 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.
-
返回值
范例
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);
?>
CDN