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dio_seek

(PHP 4 >= 4.2.0, PECL)

dio_seek -- Seeks to pos on fd from whence

说明

int dio_seek ( resource fd, int pos [, int whence] )

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

例

例子 1. Setting the baud rate on a serial port

<?php

$fd = dio_open('/dev/ttyS0', O_RDWR);

dio_seek($fd, SEEK_SET, 10);
// position is now at 10 characters from the start of the file

dio_seek($fd, SEEK_CUR, -2);
// position is now at 8 characters from the start of the file

dio_seek($fd, SEEK_END, 5);
// position is now at 5 characters from the end of the file

dio_seek($fd, SEEK_END, -10);
// 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);
?>

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