What is the default subscript of a php array?

The subscript of the php array is an integer type by default and starts from 0. In php, if you do not manually set the string key name (subscript) when creating an array, an index array will be created by default. Its subscript (key name) consists of an integer value, and the default index value increases sequentially starting from 0. ;Each number corresponds to the position of an array element in the array and does not need to be specified.

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

You can use the following two methods to declare an array in PHP Method:

• Declare the array by directly assigning values ​​to the array elements;

• Use the array() function to declare the array.

But no matter which method, if you do not manually set the string key name (subscript) when creating the array, the index array will be created by default

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$array[] = &#39;苹果&#39;;
$array[] = &#39;香蕉&#39;;
$array[] = &#39;梨&#39;;
$array[] = &#39;桃子&#39;;
var_dump($array);
?>

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$array = array(&#39;红色&#39;,&#39;黄色&#39;,&#39;蓝色&#39;,&#39;白色&#39;);

var_dump($array);
?>

The subscript (key name) of the index array consists of integer values ​​and starts from 0 by default. Each number corresponds to the position of an array element in the array. It is not required Specifically, PHP will automatically assign an integer value to the key name of the index array, and then automatically increment from this value.

Only when the string key name is manually specified, the associative array will be set:

<?php
header(&#39;content-type:text/html;charset=utf-8&#39;);   
$array = array("id"=>25,"name"=>"李华","age"=>18);

var_dump($array);
?>

The key name of the associative array can be any integer or string. If the key name is a string, add a delimiting modifier to the key name - single quotes ' ' or double quotes " ". For indexed arrays, in order to avoid confusion, it is best to add delimiters.

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