Shared Memory 函数
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shmop_read

(PHP 4 >= 4.0.4, PHP 5)

shmop_read — Read data from shared memory block

说明

string shmop_read ( int $shmid , int $start , int $count )

shmop_read() will read a string from shared memory block.

参数

shmid

The shared memory block identifier created by shmop_open()

start

Offset from which to start reading

count

The number of bytes to read

返回值

Returns the data 或者在失败时返回 FALSE.

范例

Example #1 Reading shared memory block

<?php
$shm_data = shmop_read($shm_id, 0, 50);
?>

This example will read 50 bytes from shared memory block and place the data inside $shm_data.

参见

Shared Memory 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: Read data from shared memory block

用户评论:

Milan Cvejic (18-Feb-2009 09:35)

You should always serialize data written in shared memory.
And when you are reading data you should always unserialize.

<?php

$data = 'test';
$shm_bytes_written = shmop_write($shm_id, serialize($data), 0);
$shm_data = unserialize(shmop_read($shm_id, 0, $shm_bytes_written));
?>

Craig Manley (07-Jan-2005 10:19)

shmop_read() reads and returns the whole memory segment's data. This is not useful if you're just working with strings. If you need to read a string from shared memory, call str_from_mem() on the result of shmop_read(). Similarly when writing strings to memory (instead of binary data), null terminate your strings with str_to_nts() before passing the value on to shmop_write().

function str_to_nts($value) {
  return "$value\0";
}

function str_from_mem(&$value) {
  $i = strpos($value, "\0");
  if ($i === false) {
    return $value;
  }
  $result =  substr($value, 0, $i);
  return $result;
}

slavapl at mailandnews dot com (02-May-2001 08:15)

Also you can use the shmop_size() function to determine the block size.

macmaster at pobox dot com (30-Mar-2001 08:01)

When i need to read the whole string at that shm pointer, setting the count parameter to zero (0) seems work for me.