3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array = [1,1,1,2,2,3,3,4,1,1,2,2,3]; var_export( json_decode( preg_replace_callback( '/\b(\d+)(?:,\1)*\b/', function($m) { return sprintf( '{"%d":%d}', $m[1], count(explode(',', $m[0])) ); }, json_encode($array) ), true ) );
Output for 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 - 8.3.4, 8.3.6 - 8.3.25, 8.4.1 - 8.4.12
array ( 0 => array ( 1 => 3, ), 1 => array ( 2 => 2, ), 2 => array ( 3 => 2, ), 3 => array ( 4 => 1, ), 4 => array ( 1 => 2, ), 5 => array ( 2 => 2, ), 6 => array ( 3 => 1, ), )
Output for 8.3.5
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0 array ( 0 => array ( 1 => 3, ), 1 => array ( 2 => 2, ), 2 => array ( 3 => 2, ), 3 => array ( 4 => 1, ), 4 => array ( 1 => 2, ), 5 => array ( 2 => 2, ), 6 => array ( 3 => 1, ), )

preferences:
144.81 ms | 408 KiB | 5 Q