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/
Naming
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Last update: 20-02-2022
Naming constraints
It is possible to create variables whose names do not follow naming constraints.
/**
* It is possible to create variables whose names ...
* do not follow the naming constraints.
*
* Variable variables are a very powerful tool, ...
* and should be used with extreme care.
*
* Their improper use can lead to some significant security issues.
*/
$name = '123';
$$name = '456';
echo $$name; // 456
echo ${'123'}; // 456
/**
* Security issues ...
*/
$debug = false;
$_POST = array('debug' => 1);
extract($_POST);
if ($debug) {
echo "sql queries"; // debug is true!
}
A technique similar to variable variables can also be used to hold function names:

/**
* Variable name for functions
*/
function myFunc() {
echo 'function code';
}
$echo = 'myFunc';
$echo();
// function code
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