Question

我有两个arrays - 一个single和其他multi-dimensional。

$abc='["first","second","third","fourth"]';

$def='[{"post_id":"1","postid":"42","tags":["eminem","baby","jordan"]},{"post_id":"3","postid":"38","tags"
:["abc","def","jordan"]},{"post_id":"4","postid":"40","tags":["eminem","baby","first","second","fourth"
]}]';

$ghi=json_decode($def,true);
$jkl=json_decode($abc,true);


echo '<pre>';
print_r($jkl);
echo '</pre>';

echo '<pre>';
print_r($ghi);

echo '</pre>';

这就是它的样子：

Array
(
    [0] => first
    [1] => second
    [2] => third
    [3] => fourth
)

Array
(
    [0] => Array
        (
            [post_id] => 1
            [postid] => 42
            [tags] => Array
                (
                    [0] => eminem
                    [1] => baby
                    [2] => jordan
                )

        )

    [1] => Array
        (
            [post_id] => 3
            [postid] => 38
            [tags] => Array
                (
                    [0] => abc
                    [1] => def
                    [2] => jordan
                )

        )

    [2] => Array
        (
            [post_id] => 4
            [postid] => 40
            [tags] => Array
                (
                    [0] => eminem
                    [1] => baby
                    [2] => first
                    [3] => second
                    [4] => fourth
                )

        )

)

我要做的是在多维数组中存在的子数组tags内搜索单维数组的元素。

这是我的代码：

$users = array_unique($jkl);
$array = [];
$i=0;   

foreach($users as $user) 
{

    if (in_array($user, $ghi[$i]['tags'])) 
    {
        $newdata =  array (
            'postId' => $ghi[$i]['postid'],
            'tag' => $user
         );
        array_push($array, $newdata);
    }
    $i++;
}

但是我得到了错误提到的问题标题。可能的原因是什么？谢谢！

Answer 1

您的两个数组都有不同数量的元素。第一个数组有四个元素，第二个数组有三个元素。这就是你遇到问题的原因。

您应该检查变量是否已设置且必须是数组。使用!empty()和is_array()

foreach($users as $k=>$user){
  if(!empty($ghi[$k]['tags']) && is_array($ghi[$k]['tags'])) { // check this condition here
    if (in_array($user, $ghi[$k]['tags'])){
        $newdata =  array (
            'postId' => $ghi[$k]['postid'],
            'tag' => $user
         );
        array_push($array, $newdata);
    }
  }  
}

注意： - 我使用数组密钥$k代替$i

Answer 2

您必须遍历multi-dimensional数组并执行您想要的操作： -

<?php

$abc='["first","second","third","fourth"]';

$def='[{"post_id":"1","postid":"42","tags":["eminem","baby","jordan"]},{"post_id":"3","postid":"38","tags"
:["abc","def","jordan"]},{"post_id":"4","postid":"40","tags":["eminem","baby","first","second","fourth"
]}]';

$ghi=json_decode($def,true);
$jkl=json_decode($abc,true);

$users = array_unique($jkl);
$array = []; // empty array
foreach($ghi as $gh)  // iterate through multi-dimensional array not single one
{
for($i=0;$i<count($users);$i++){ // a for loop to iterate through single-dimensional completly
    if (in_array($users[$i],$gh['tags']))  // if single dimensional array value exist in multi-dimensional tags array
    {
        $newdata =  array (
            'postId' => $gh['postid'],
            'tag' => $users[$i]
         );
        array_push($array, $newdata); // push the data
    }
   }
}
echo "<pre/>";print_r($array); // print newly created array
?>

输出： - https://eval.in/602523

注意： - 尝试将变量名称设置为不会产生歧义。谢谢

Answer 3

这是因为2个数组的长度不同，请使用isset()删除错误：

因为$ghi数组的第三个索引不存在，并且它尝试获取$ghi[3]['tags'] - 这就是错误发生的原因

尝试：

foreach($users as $user) 
{
    if(isset($ghi[$i]['tags'])) { // just add this condition here
      if (in_array($user, $ghi[$i]['tags'])) 
      {
          $newdata =  array (
              'postId' => $ghi[$i]['postid'],
              'tag' => $user
           );
          array_push($array, $newdata);
      }
    }
    $i++;
}

Answer 4

这取决于您要搜索的内容。如果你想要检查$ ghi数组中的所有$ users，那么你需要每次都循环遍历。

foreach($users as $user)
{
  for ($i = 0; $i < count($ghi); $i++) {
    if (in_array($user, $ghi[$i]['tags']))
    {
        $newdata =  array (
            'postId' => $ghi[$i]['postid'],
            'tag' => $user
         );
        array_push($array, $newdata);
    }
  }
}

这将导致$ newdata由以下

组成

array(2) { ["postId"]=> string(2) "40" ["tag"]=> string(6) "fourth" }

但是如果你只想要检查每个数组一次。然后你需要检查以确保你没有走出界限。

$ ghi中只有3个元素。 $ users中有4个元素。

所以你可以循环遍历foreach中较小的数组 - 切换$ users - ＆gt; $ GHI 或者在foreach循环中检查$ ghi在$ i是什么时候有一个有效元素。

d

PHP- in_array（）期望参数2是数组

4 个答案: