shmop_read

(PHP 4 >= 4.0.4, PHP 5)

shmop_readLit des données à partir d'un bloc

Description

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

shmop_read() lit une chaîne dans une bloc de mémoire partagée.

Liste de paramètres

shmid

L'identifiant du bloc mémoire partagé, créé par la fonction shmop_open()

start

Position depuis laquelle on doit commencer à lire

count

Le nombre d'octets à lire

Valeurs de retour

Retourne les données ou FALSE si une erreur survient.

Exemples

Exemple #1 Lit un bloc de mémoire partagée

<?php
$shm_data 
shmop_read($shm_id050);
?>

Cet exemple lit 50 octets dans le bloc de mémoire partagée et les place dans $shm_data.

Voir aussi

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User Contributed Notes 4 notes

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2
Craig Manley
9 years ago
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;
}
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0
slavapl at mailandnews dot com
12 years ago
Also you can use the shmop_size() function to determine the block size.
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0
macmaster at pobox dot com
13 years ago
When i need to read the whole string at that shm pointer, setting the count parameter to zero (0) seems work for me.
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-2
Milan Cvejic
5 years ago
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));
?>
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