如何在PHP中获取空索引foreach循环

Question

这里我有一个数组，使用此数组，我必须获取index，例如它具有空值或空值，我对其进行了搜索，但是我没有得到预期的答案，请参见下面的内容，我已经发布了我的预期的答案。

  

print_r（$ val）;

    Array
(
    [id] => 4 A
    [tripID] => 
    [startFrom] => 1
    [limit] => 20
    [cabID] => 
)

  

预期答案

1. tripID
2. cabID

Answer 1

这应该有帮助-

=Arrayformula(if(or(importrange(H2,"Sheet1!C2:C")="Mosque",
importrange(H2,"Sheet1!C2:C")="Church",
importrange(H2,"Sheet1!C2:C")="Temple"),
proper(query(importrange(H2,"Sheet1!A2:D"), "Select Col3 Where Col1 = 'New' And Col4 = 'Done'")),
lower(query(importrange(H2,"Sheet1!A2:D"),"Select Col3 Where Col1 = 'New' And Col4 = 'Done'"))))

输出

$a = array
(
    'ID' => '4 A',
    'tripID' => '',
    'startFrom' => 1,
    'limit' => 20,
    'cabID' => '',
);
// Filter array if value is  blank or null but not 0
$check = array_filter($a, function($v) {
  return $v == '' || $v == null;
});
// Extract the keys
print_r(array_keys($check));

array_filter()

Answer 2

此功能应将您带向正确的方向array_filter。请注意，这似乎是一个家庭作业的问题。