这是一个坏主意，但似乎是一个有趣的挑战，没有foreach：

$arr = 
[
  [
    "item" =>"AABBCC",
    "quants" => "1",
  ],
  [
    "item" => "AABBCC", 
    "quants" => "1",
  ],
  [
    "item" => "SLF02", 
    "quants" => "1",
  ],
  [
    "item" => "SLF02", 
    "quants" => "3",
  ]
];

$arr = array_values(call_user_func_array("array_merge", array_map(function($i) use ($arr) {
  return [$i["item"] => ["item" => $i["item"], "quants" => array_reduce(
    array_filter($arr, function($j) use ($i) {
        return $j["item"] == $i["item"]; 
    }), function($carry, $item) { 
        return $carry + $item["quants"]; 
    })
  ]];
}, $arr)));

var_dump($arr);

/*
array(2) {
  [0]=>
  array(2) {
    ["item"]=>
    string(6) "AABBCC"
    ["quants"]=>
    int(2)
  }
  [1]=>
  array(2) {
    ["item"]=>
    string(5) "SLF02"
    ["quants"]=>
    int(4)
  }
}
*/

以下是我的方法：

<?php
$array = array(
    array('item'=>'AABBCC','quants'=>1),
    array('item'=>'AABBCC','quants'=>1),
    array('item'=>'SLF02','quants'=>1),
    array('item'=>'SLF02','quants'=>3),
);

$summed_array = array();

foreach($array as $row){
    $key = $row['item'];

    if(!isset($summed_array[$key])){
        $summed_array[$key] = array(
            'item' => $row['item'],
            'quants' => 0
        );
    }

    $summed_array[$key]['quants'] += $row['quants'];
}

// turn the array back to a 0 based array
$summed_array = array_values($summed_array);

echo '<pre>',print_r($summed_array),'</pre>';