3v4l.org

run code in 200+ php & hhvm versions
<?php $a = &$b; var_dump(implode(',', array_keys(get_defined_vars())));
based on 3bsvS
Output for 7.0.0 - 7.3.1
string(47) "_GET,_POST,_COOKIE,_FILES,argv,argc,_SERVER,a,b"
Output for 5.4.0 - 5.6.25
string(47) "_GET,_POST,_COOKIE,_FILES,argv,argc,_SERVER,b,a"
Output for 5.0.0 - 5.3.29
string(162) "GLOBALS,_ENV,HTTP_ENV_VARS,argv,argc,_POST,HTTP_POST_VARS,_GET,HTTP_GET_VARS,_COOKIE,HTTP_COOKIE_VARS,_SERVER,HTTP_SERVER_VARS,_FILES,HTTP_POST_FILES,_REQUEST,b,a"
Output for 4.3.2 - 4.4.9
string(154) "argv,argc,HTTP_POST_VARS,_POST,HTTP_GET_VARS,_GET,HTTP_COOKIE_VARS,_COOKIE,HTTP_SERVER_VARS,_SERVER,HTTP_ENV_VARS,_ENV,HTTP_POST_FILES,_FILES,_REQUEST,b,a"
Output for 4.3.0 - 4.3.1
string(144) "HTTP_POST_VARS,_POST,HTTP_GET_VARS,_GET,HTTP_COOKIE_VARS,_COOKIE,HTTP_SERVER_VARS,_SERVER,HTTP_ENV_VARS,_ENV,HTTP_POST_FILES,_FILES,_REQUEST,b,a"