shmop_read

Description

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

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

shmop_read() takes 3 parameters: shmid, which is the shared memory block identifier created by shmop_open(), offset from which to start reading and count on the number of bytes to read.

例子 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.

add a note User Contributed Notes

Craig Manley
08-Jan-2005 06:19


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
03-May-2001 03:15


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

macmaster at pobox dot com
31-Mar-2001 04:01


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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