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This article mainly explains "how to flexibly use foreach+list in PHP to deal with multi-dimension". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "how to flexibly use foreach+list to deal with multi-dimension in PHP".

Flexible use of foreach+list to deal with Multi-dimensional arrays in PHP

Throw the question first. Sometimes the parameters we receive are multidimensional arrays, and we need to convert them to normal arrays, such as:

1$ arr = [

2 [1, 2, [3, 4]]

3 [5, 6, [7, 8]]

4]

What we need is that element 1 becomes 1, 2, and element 2 becomes 5, 6, 7, and 8, respectively. At this point, we can implement it with foreach and list, and it's very simple:

1foreach ($arr as list ($a, $b, list ($c, $d)) {

2 echo $a,',', $b,',', $c,',', $d, PHP_EOL

3}

Isn't it very simple. Note, however, that list should specify the key name when disassembling the Hash array in the form of key-value pairs, and it can only be used in versions after 7.1.

1$ arr = [

2 ["a" = > 1, "b" = > 2]

3 ["a" = > 3, "b" = > 4]

4]

five

6foreach ($arr as list ("a" = > $a, "b" = > $b)) {

7 echo $a,',', $b, PHP_EOL

8}

nine

10foreach ($arr as ["a" = > $a, "b" = > $b]) {

11 echo $a,',', $b, PHP_EOL

12}

Note: if there is no key name, the output will be empty and will not report an error, this is a BUG point, be sure to pay attention.

The second way of writing in the above code is more simple and intuitive, which shows that we can also disassemble arrays in this way. And when you specify the key values, you don't have to care about their order:

1 ["b" = > $b, "a" = > $a] = $arr [0]

2echo $a,',', $b, PHP_EOL

It turns out that list () still has such grammatical candy, sure enough, we still have to keep learning, and the methods that have been used but have never been thoroughly understood can be of so much use. Say no more, and go on to study the other interesting things in the manual!

Test code: https://github.com/zhangyue0503/dev-blog/blob/master/php/201911/source/%E5%9C%A8PHP%E4%B8%AD%E7%81%B5%E6%B4%BB%E4%BD%BF%E7%94%A8foreach%2Blist%E5%A4%84%E7%90%86%E5%A4%9A%E7%BB%B4%E6%95%B0%E7%BB%84.php

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