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<?php function hash_equals($a, $b) { return substr_count($a ^ $b, "\0") * 2 === strlen($a . $b); } var_dump(hash_equals("a", "a"));
Output for 5.6.0 - 5.6.30, 7.0.0 - 7.0.18, 7.1.0 - 7.1.4
Fatal error: Cannot redeclare hash_equals() in /in/vFave on line 5
Process exited with code 255.
Output for 5.5.0 - 5.5.38
bool(true)

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