数组加减有关问题

<br />
//数组a：<br />
array (<br />
  0 => <br />
  array (<br />
    'cust_no' => '310F6 1VA5A',<br />
    'lotno' => '2X15',<br />
    'part_count' => '32',<br />
  ),<br />
  1 => <br />
  array (<br />
    'cust_no' => '310F6 1VA5A',<br />
    'lotno' => '2Z25',<br />
    'part_count' => '32',<br />
  ),<br />
)<br />
<br />
//数组b：<br />
<br />
array (<br />
  0 => <br />
  array (<br />
    'cust_no' => '310F6 1VA5A',<br />
    'total' => '48',<br />
  ),<br />
)<br />

<br />
//数组a：<br />
array (<br />
  0 => <br />
  array (<br />
    'cust_no' => '310F6 1VA5A',<br />
    'lotno' => '2X15',<br />
    'part_count' => '32',<br />
  ),<br />
  1 => <br />
  array (<br />
    'cust_no' => '310F6 1VA5A',<br />
    'lotno' => '2Z25',<br />
    'part_count' => '16',<br />
  ),<br />
)<br />

<br />
//数组a：<br />
array (<br />
  0 => <br />
  array (<br />
    'cust_no' => '310F6 1VA5A',<br />
    'lotno' => '2X15',<br />
    'part_count' => '0',<br />
  ),<br />
  1 => <br />
  array (<br />
    'cust_no' => '310F6 1VA5A',<br />
    'lotno' => '2Z25',<br />
    'part_count' => '16',<br />
  ),<br />
)<br />