What is an array in PHP

#An array in PHP is actually an ordered map. A mapping is a type that associates values ​​to keys.

This type has been optimized in many aspects, so it can be treated as a real array, or list (vector), hash table (an implementation of mapping), dictionary, set , stacks, queues and many more possibilities.

Since the value of an array element can also be another array, tree structures and multidimensional arrays are also allowed.

Define array array() (Recommended learning: PHP programming from entry to proficiency)

You can use the array() language structure to create a new one array. It accepts any number of comma-separated key => value pairs.

array(  key =>  value<br/>     , ...<br/>     )<br/>// 键（key）可是是一个整数 integer 或字符串 string<br/>// 值（value）可以是任意类型的值<br/>

The comma after the last array element can be omitted. Usually used in single-line array definitions, such as array(1, 2) instead of array(1, 2,). It is common to leave the last comma in multi-line array definitions to make it easier to add a new cell.

Since 5.4, you can use the short array definition syntax, using [] instead of array().

<?php<br/>$array = array(<br/>    "foo" => "bar",<br/>    "bar" => "foo",<br/>);<br/><br/>// 自 PHP 5.4 起<br/>$array = [<br/>    "foo" => "bar",<br/>    "bar" => "foo",<br/>];<br/>?><br/>

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