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@ 2022-09-19T21:06:12Z

<?php

$arr = [
    [
        'user_id' => 120,
        'username' => 'test1',
        'count' => 2
    ],
    [
        'user_id' => 120,
        'username' => 'test1',
        'count' => 3
    ],
    [
        'user_id' => 110,
        'username' => 'test2',
        'count' => 2
    ]
];

/** loop through "$arr" and sum the "count" values based on the "user_id" */
$result = array_reduce($arr, function ($a, $c) {
    /** index the resulting array by the "user_id" value which allows for instant lookup in case of duplicate "user_id" value */
    $a[$c['user_id']] = [
        'user_id' => $c['user_id'],
        'username' => $c['username'],
        /** sum the "count" values
         * the first iteration will have an empty array
         * so we should check for existance before getting the value in order to prevent bugs
         */
        'count' => ($a[$c['user_id']]['count'] ?? 0) + $c['count']
    ];
    return $a;
}, []);

var_export($result);

Output for git.master, git.master_jit, rfc.property-hooks: array ( 120 => array ( 'user_id' => 120, 'username' => 'test1', 'count' => 5, ), 110 => array ( 'user_id' => 110, 'username' => 'test2', 'count' => 2, ), )

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2022-12-01 RFC: Property hooks - included in PHP 8.4
2020-03-21 RFC: Is_Literal - declined
2020-12-04 Enumerations - included in PHP 8.1
2018-06-15 Typed Properties v2 - implemented in PHP 7.4
2016-08-12 Object typehint - included in PHP 7.2
2016-08-14 Arrow functions - withdrawn
2016-05-29 array_change_keys() - withdrawn
2016-04-19 Lexical scope support for anonymous classes - suspended
2016-04-17 Functional Interfaces - declined
2016-03-16 Typed Properties - superseded in favor of Typed Properties 2.0
2015-08-27 Callable Prototypes - declined
2015-05-01 Short Closures - declined / withdrawn in favor of Arrow Functions
2015-02-18 Scalar type hints v5 - included in PHP 7
2015-02-14 Union Types - declined
2013-09-22 Anonymous classes - included in PHP 7

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