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<?php $a = ['2018-05'=> '15', '2018-06'=> '100']; $b = ['2018-05'=> '5']; $years = array_map(NULL, $a, $b); $years = array_combine(array_keys($a), $years); $differences = array_map(function ($year_diffs) : float { // Did we get a pair to compare? $has_diff = isset($year_diffs[0]) and isset($year_diffs[1]); // If we got a pair then compare, else assume we got one. $diff = $has_diff ? abs($year_diffs[0] - $year_diffs[1]) : $year_diffs[0]; return $diff; }, $years); var_dump($differences);
Output for 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 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 - 8.3.27, 8.4.1 - 8.4.14
array(2) { ["2018-05"]=> float(10) ["2018-06"]=> float(100) }
Output for 5.6.0 - 5.6.40
Parse error: syntax error, unexpected ':', expecting '{' in /in/BSEui on line 9
Process exited with code 255.
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