英文:
Get max date from a nested array
问题
如何从以下数组中获取最大的到期日期？到期日期始终是具有键5的值数组中的值，即$results['values'][5]。
我知道可以对于简单的数组执行以下操作：
$max = max(array_map('strtotime', $arr));
echo date('d F Y', $max);
如何在嵌套数组中实现相同的效果？
英文:
If I have the following array how can I get the max expiry date? The expiry date is always the value in the values array with key 5 i.e. $results['values']['5']
array (
0 =>
array (
'values' =>
array (
1 => '123456',
2 => 'Blue',
3 => 'Container',
4 => '03-01-2020', // start date
5 => '03-01-2021', // exp date
6 => '',
7 => '',
),
),
1 =>
array (
'values' =>
array (
1 => '21312',
2 => 'Green',
3 => 'Box',
4 => '2019-04-12', // start date
5 => '', //exp date
6 => '',
7 => '',
),
),
2 =>
array (
'values' =>
array (
1 => '434324',
2 => 'Orange',
3 => 'Box',
4 => '2018-04-28', // start date
5 => '2019-04-23', // exp date
6 => '',
7 => '',
),
),
)
I know I can do something as follows for a simple array:
$max = max(array_map('strtotime', $arr));
echo date('d F Y', $max);
How can I achieve the same with a nested array?
答案1
得分: 3
自定义函数可提取到期日期并一次性使用 strtotime，因为您已经在使用 array_map：
$expiryDates = array_map(static function ($entry) {
return strtotime($entry['values'][5]);
}, $input);
echo date('d F Y', max($expiryDates));
演示：https://3v4l.org/AiFtA
奖励 - 使用 PHP 7.4 短闭包：
$expiryDates = array_map(fn($entry) => strtotime($entry['values'][5]), $input);
echo date('d F Y', max($expiryDates));
英文:
Since you're already using array_map, you may use a custom function that grabs the expiry date and uses strtotime on it in one go:
$expiryDates = array_map(static function ($entry) {
return strtotime($entry['values'][5]);
}, $input);
echo date('d F Y', max($expiryDates));
Demo: https://3v4l.org/AiFtA
Bonus - using PHP 7.4 short closures:
$expiryDates = array_map(fn($entry) => strtotime($entry['values'][5]), $input);
echo date('d F Y', max($expiryDates));
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