3v4l.org

run code in 200+ php & hhvm versions
<?php function foo(&$str) { $str = 'xyz'; return $str; } $o = "abc"; foo($o); var_dump($o); $o = "abc"; call_user_func('foo', $o); var_dump($o); $o = "abc"; call_user_func('foo', [$o]); var_dump($o); $a[] = "abc"; $a[] = "abc"; $a[] = "abc"; call_user_func('foo', array_slice($a, 0, 1)); var_dump($a);
based on KNM3k
Output for 7.1.0 - 7.2.6
string(3) "xyz" Warning: Parameter 1 to foo() expected to be a reference, value given in /in/OEOA1 on line 12 string(3) "abc" Warning: Parameter 1 to foo() expected to be a reference, value given in /in/OEOA1 on line 15 string(3) "abc" Warning: Parameter 1 to foo() expected to be a reference, value given in /in/OEOA1 on line 21 array(3) { [0]=> string(3) "abc" [1]=> string(3) "abc" [2]=> string(3) "abc" }
Output for 7.0.0 - 7.0.8, 7.0.10 - 7.0.20
string(3) "xyz" string(3) "xyz" string(3) "abc" Warning: Parameter 1 to foo() expected to be a reference, value given in /in/OEOA1 on line 21 array(3) { [0]=> string(3) "abc" [1]=> string(3) "abc" [2]=> string(3) "abc" }
Output for 7.0.9
string(3) "xyz" Warning: Parameter 1 to foo() expected to be a reference, value given in /in/OEOA1 on line 12 string(3) "abc" string(3) "abc" Warning: Parameter 1 to foo() expected to be a reference, value given in /in/OEOA1 on line 21 array(3) { [0]=> string(3) "abc" [1]=> string(3) "abc" [2]=> string(3) "abc" }
Output for 5.6.0 - 5.6.26
string(3) "xyz" Warning: Parameter 1 to foo() expected to be a reference, value given in /in/OEOA1 on line 12 string(3) "abc" string(3) "abc" array(3) { [0]=> string(3) "abc" [1]=> string(3) "abc" [2]=> string(3) "abc" }