PHP has an array of features which

PHP array is a very powerful and flexible data types. The following is a PHP array with some of the features:

1, may be used as an array or string of digital key

$arr = [1 => 'ok', 'one' => 'hello'];

2, the array can be sequentially read

foreach($arr as $key => $value){
 echo $arr[$key];
}

3, the random read elements in the array

$arr = [1 => 'ok', 'one' => 'hello', 'a' => 'world'];

echo $arr['one'];

echo current($arr);

4, the length of the array is variable

$arr = [1, 2, 3];

$arr[] = 4;

array_push($arr, 5);

It is based on these characteristics, we can easily achieve collection, stack, lists, dictionaries and other data structures using arrays in PHP.