Programming

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Variables / Variable Variable

Variable variables

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

$debug = false; // Look Here
$_POST = array('debug' => 1);
extract($_POST);

var_dump($debug == true); // true - Security issue

Functions

A technique similar to variable variables can also be used to hold function names. 
 
/**
 * Variable name for functions
 */

function myFunc() {
    echo 'code';
}

$echo = 'myFunc';
$echo(); // code




References