Copy data from named shared memory

# SyncSharedMemory::read

(PECL sync >= 1.1.0)

SyncSharedMemory::read — Copy data from named shared memory

### 説明

public SyncSharedMemory::read ([ int `$start` = 0 [, int `$length` ]] )

Copies data from named shared memory.

### パラメータ

`start`

  The start/offset, in bytes, to begin reading.

  > 注意:

  > If the value is negative, the starting position will begin at the specified number of bytes from the end of the shared memory segment.

`length`

  The number of bytes to read.

  > 注意:

  > If unspecified, reading will stop at the end of the shared memory segment.

  > If the value is negative, reading will stop the specified number of bytes from the end of the shared memory segment.

### 返り値

A string containing the data read from shared memory.

### 例

例1 SyncSharedMemory::__construct() example

`<?php
// You will probably need to protect shared memory with other synchronization objects.
// Shared memory goes away when the last reference to it disappears.
$mem = new SyncSharedMemory("AppReportName", 1024);
if ($mem->first())
{
// Do first time initialization work here.
}
$result = $mem->write("report.txt");
$result = $mem->read(3, -4);
var_dump($result);
?>`

上の例の出力は、 たとえば以下のようになります。

    string(3) "ort"

### 参考

- SyncSharedMemory::__construct() - Constructs a new SyncSharedMemory object
- SyncSharedMemory::first() - Check to see if the object is the first instance system-wide of named shared memory
- SyncSharedMemory::write() - Copy data to named shared memory
- SyncSharedMemory::read()