Online PHP editor | output for ULAkV

@ 2019-09-18T20:24:07Z

<?php
$numbers = [4, 3, 4, 3, 1, 2, 1];
var_export(
    array_keys(
        array_intersect(
            array_count_values($numbers),
            [1]
        )
    )
);

echo "\n---\n";
var_export(
    array_keys(
        array_filter(
            array_count_values($numbers),
            function($count) {
                return $count === 1;
            }
        )
    )
);

echo "\n---\n";
// PHP7.4+
var_export(
    array_keys(
        array_filter(
            array_count_values($numbers),
            fn($count) => $count === 1
        )
    )
);

Output for 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3: array ( 0 => 2, ) --- array ( 0 => 2, ) --- array ( 0 => 2, )
Output for 7.3.0 - 7.3.33: Parse error: syntax error, unexpected '=>' (T_DOUBLE_ARROW), expecting ')' in /in/ULAkV on line 30
Process exited with code 255.
Output for 7.1.0 - 7.1.33, 7.2.0 - 7.2.34: Parse error: syntax error, unexpected '=>' (T_DOUBLE_ARROW), expecting ',' or ')' in /in/ULAkV on line 30
Process exited with code 255.

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