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shmop_readLê dados de um bloco de memória compartilhada


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

shmop_read() irá ler uma string de um bloco de memória compartilhada.

shmop_read() pega 3 parâmetros: shmid, que é o identificador do bloco de memória compartilhada criado por shmop_open(), e o último que começa lendo e contando o número de bytes para ler.

Exemplo #1 Lendo um bloco de memória compartilhada


Esse exemplo irá ler 50 bytes de um bloco de memória compartilhada e armazenaros dados dentro de $shm_data.

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User Contributed Notes 5 notes

Craig Manley
17 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;
macmaster at pobox dot com
21 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.
michael dot wuertz at six dot de
1 year ago
With shmop_read, you probably get a "\0" - padded string.

$zero_padded = shmop_read($shm_seg, 0, 128);

$usable_string = rtrim($zero_padded, "\0");
slavapl at mailandnews dot com
21 years ago
Also you can use the shmop_size() function to determine the block size.
Milan Cvejic
13 years ago
You should always serialize data written in shared memory.
And when you are reading data you should always unserialize.


= '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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