PHP foreach 加&遍历的同时改变原数组即修改数据或者增加数据

深碍√TFBOYSˉ_ 2022-03-27 12:35 184阅读 0赞

注意：如果我要改变数组某一个值 直接遍历的话原数组是不会变的  
$data=array(1,2,3,4);  
foreach($data as $k=>$v)\{  
       if($v==2)  $v=666;//我们想把值等于2的改为666 这样的话在内部改变了$v但是$data还是没改变

下面提供两种方法

1.使用键名的方式

foreach($data as $k => $v)\{  
      if($v==2)  $data\[$k\]=666;  
\}

2.我们可以在遍历的值前面加个&符号这样就可以改变原数组了  
foreach($data as &$v)\{  
      if($v==2)  $v=666;//因为$v前面加了'&'所以原数组就直接改变了  
\}

场景：每个产品可能有多个链接，统计每个产品各个链接下的注册数reg_amount，
    同时要返回给前端产品名称，id；url名称，id；注册数
    $ret = [
      [
        'product_id' => 1,
        'url_id' => 1,
        'reg_amount' => 0
      ],
      [
        'product_id' => 1,
        'url_id' => 2,
        'reg_amount' => 0
      ],
      [
        'product_id' => 2,
        'url_id' => 3,
        'reg_amount' => 0
      ]
    ];
    
    $retTemp = [
      [
        'product_id' => 1,
        'product_name' => '钱包',
        'url_id' => 1,
        'url_name' => '钱包链接1'
      ],
      [
        'product_id' => 1,
        'product_name' => '钱包',
        'url_id' => 2,
        'url_name' => '钱包链接2'
      ],
      [
        'product_id' => 2,
        'product_name' => '鞋子',
        'url_id' => 3,
        'url_name' => '鞋子链接1'
      ]
    ];

方式一
    foreach ($ret as $key => $value) {
        foreach ($tempRet as $k => $v) {
            if($value['product_id'] == $v['product_id'] && $value['url_id'] == $v['url_id']) {
              $ret[$key]['product_name'] = $v['product_name'];
              $ret[$key]['url_name'] = $v['url_name'];
    
            }
    
        }
    }

方式二

foreach ($ret as $key => &$value) {
        foreach ($tempRet as $k => $v) {
            if($value['product_id'] == $v['product_id'] && $value['url_id'] == $v['url_id']) {
              $value['product_name'] = $v['product_name'];
              $value['url_name'] = $v['url_name'];
    
            }
    
        }
    }