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run code in 150+ php & hhvm versions
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<?php $tree = array( 1 => array( 'parent_id' => null, 'name' => 'root', 'depth' => 0, ), 11 => array( 'parent_id' => 1, 'name' => 'a', 'depth' => 1, ), 12 => array( 'parent_id' => 1, 'name' => 'b', 'depth' => 1, ), 111 => array( 'parent_id' => 11, 'name' => 'aa', 'depth' => 2, ), 2 => array( 'parent_id' => null, 'name' => 'other root', 'depth' => 0, ) ); foreach ($tree as $key => &$sub) { if (isset($sub['parent_id'])) { $tree[$sub['parent_id']]['children'][$key] = &$sub; } } unset($sub); // unset the reference to make sure to not overwrite it later... // now remove the entries with parents foreach ($tree as $key => $sub) { if (isset($sub['parent_id'])) unset($tree[$key]); } var_dump(json_encode($tree));
Output for 5.2.0 - 7.1.0
string(256) "{"1":{"parent_id":null,"name":"root","depth":0,"children":{"11":{"parent_id":1,"name":"a","depth":1,"children":{"111":{"parent_id":11,"name":"aa","depth":2}}},"12":{"parent_id":1,"name":"b","depth":1}}},"2":{"parent_id":null,"name":"other root","depth":0}}"
Output for 5.0.0 - 5.1.6
Fatal error: Call to undefined function json_encode() in /in/EBg92 on line 43
Process exited with code 255.
Output for 4.4.2 - 4.4.9
Parse error: syntax error, unexpected '&', expecting T_VARIABLE or '$' in /in/EBg92 on line 31
Process exited with code 255.
Output for 4.3.0 - 4.3.1, 4.3.5 - 4.4.1
Parse error: parse error, unexpected '&', expecting T_VARIABLE or '$' in /in/EBg92 on line 31
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error, expecting `T_VARIABLE' or `'$'' in /in/EBg92 on line 31
Process exited with code 255.