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<?php $counts = array(); $item = 2; $counts[$item] = ($counts[$item] ?? 0) + 1; var_dump($counts); $counts[$item] = ($counts[$item] ?? 0) + 1; var_dump($counts);
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.25, 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 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
array(1) { [2]=> int(1) } array(1) { [2]=> int(2) }
Output for 5.5.24 - 5.5.35, 5.6.8 - 5.6.28
Parse error: syntax error, unexpected '?' in /in/DMnbW on line 6
Process exited with code 255.

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