get_defined_vars

$b = array(1,1,2,3,5,8);

$arr = get_defined_vars();

// print $b
print_r($arr["b"]);

// print path to the PHP interpreter (if used as a CGI)
// e.g. /usr/local/bin/php
echo $arr["_"];

// print the command-line paramaters if any
print_r($arr["argv"]);

// print all the server vars
print_r($arr["HTTP_SERVER_VARS"]);

// print all the available keys for the arrays of variables
print_r(array_keys(get_defined_vars()));