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<?php $cities = ['New York', 'Boston', 'Los Angeles', 'Cincinnati', 'Chicago', 'Houston', 'Philadelphia', 'Dallas', 'Seattle']; $result = []; foreach ($cities as $city) { $result[$city[0]][] = $city; } var_export($result);
Output for 8.1.0 - 8.1.27, 8.1.29 - 8.1.33, 8.2.0 - 8.2.17, 8.2.19 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
array ( 'N' => array ( 0 => 'New York', ), 'B' => array ( 0 => 'Boston', ), 'L' => array ( 0 => 'Los Angeles', ), 'C' => array ( 0 => 'Cincinnati', 1 => 'Chicago', ), 'H' => array ( 0 => 'Houston', ), 'P' => array ( 0 => 'Philadelphia', ), 'D' => array ( 0 => 'Dallas', ), 'S' => array ( 0 => 'Seattle', ), )
Output for 8.2.18
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.2.18/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.2.18/modules/sodium.so.so (/usr/lib/php/8.2.18/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0 array ( 'N' => array ( 0 => 'New York', ), 'B' => array ( 0 => 'Boston', ), 'L' => array ( 0 => 'Los Angeles', ), 'C' => array ( 0 => 'Cincinnati', 1 => 'Chicago', ), 'H' => array ( 0 => 'Houston', ), 'P' => array ( 0 => 'Philadelphia', ), 'D' => array ( 0 => 'Dallas', ), 'S' => array ( 0 => 'Seattle', ), )
Output for 8.1.28
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.1.28/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.1.28/modules/sodium.so.so (/usr/lib/php/8.1.28/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0 array ( 'N' => array ( 0 => 'New York', ), 'B' => array ( 0 => 'Boston', ), 'L' => array ( 0 => 'Los Angeles', ), 'C' => array ( 0 => 'Cincinnati', 1 => 'Chicago', ), 'H' => array ( 0 => 'Houston', ), 'P' => array ( 0 => 'Philadelphia', ), 'D' => array ( 0 => 'Dallas', ), 'S' => array ( 0 => 'Seattle', ), )

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64.03 ms | 409 KiB | 5 Q