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<?php $a = new stdClass; $a->{'abc@gmail.com'} = []; $b = new stdClass; $b->{'xyz@gmail.com'} = []; $c = [$a, $b]; $arr = array_reduce($c, function ($arr, $obj) { return array_merge($arr, array_keys(get_object_vars($obj))); }, []); var_dump($arr);
Output for 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.28, 8.4.1 - 8.4.14, 8.5.0
array(2) { [0]=> string(13) "abc@gmail.com" [1]=> string(13) "xyz@gmail.com" }
Output for 8.4.15
/bin/php-8.4.15: /usr/lib/libm.so.6: version `GLIBC_2.38' not found (required by /bin/php-8.4.15) /bin/php-8.4.15: /usr/lib/libm.so.6: version `GLIBC_2.35' not found (required by /bin/php-8.4.15) /bin/php-8.4.15: /usr/lib/libc.so.6: version `GLIBC_2.34' not found (required by /bin/php-8.4.15) /bin/php-8.4.15: /usr/lib/libc.so.6: version `GLIBC_2.38' not found (required by /bin/php-8.4.15)
Process exited with code 1.

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