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shm_put_var shm_detach

Last updated: Fri, 26 Jan 2007

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# shm_get_var

(PHP 3 >= 3.0.6, PHP 4, PHP 5)

shm_get_var -- Returns a variable from shared memory

## Description

mixed shm_get_var ( int shm_identifier, int variable_key )

shm_get_var() returns the variable with a given `variable_key`, in the shared memory segment identified by `shm_identifier`. `shm_identifier` was obtained from shm_attach(). The variable is still present in the shared memory.

add a note User Contributed Notes
shm_get_var
JM
14-May-2005 03:50
`To follow up on the posts by anonymous, Bob Van Zant and chris at free-source dot com below (or, as must people inexplicably write, above) regarding the PHP warning and FALSE that shm_get_var returns if the variable key doesn't exist:
My tests (with PHP4.3.4) show that defined() is useless here. Because the function defined(string) checks whether the constant whose name is string exists, the code
<?php
if ( defined(@shm_get_var($mutex, $mutex_key)) {
...
}
?>
acts the same ("..." does not get executed) whether the variable is defined or not--unless $mutex_key happens to identify a valid string that happens to be the name of a constant. :)
Rather,
<?php
if ( @shm_get_var($mutex, $mutex_key) === FALSE ) {
...
}
?>
works, provided the object that was stored isn't actually FALSE (via <?php shm_put_var($mutex, $mutex_key, FALSE); ?>)
It would be nice to have a completely air-tight solution, though. D'oh!`
06-May-2005 02:01
`You will still receive a notice use @:
if(!defined(@shm_get_var($mutex, $mutex_key))) {
shm_put_var($mutex, $mutex_key, 0);
}`
Bob Van Zant
18-Feb-2005 12:05
`This seems to work fine to detect the lack of presence of a key in shared memory and then init it to 0 when found:
if(!defined(shm_get_var($mutex, $mutex_key))) {
shm_put_var($mutex, $mutex_key, 0);
}`
chris at free-source dot com
05-Dec-2004 02:47
`if the variable_key asked for does not exist php generates a warning and shm_get_var() will return bool(false). there doesn't seem to be a clean way to test if a key exists.`
add a note
shm_put_var shm_detach

Last updated: Fri, 26 Jan 2007
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