Are PHP array keys case sensitive?

An array is a special variable that can store multiple values ​​in a single variable. PHP array, as the name suggests, is an array in PHP. Its characteristic is to map values ​​to the type of keys. Unlike other languages, the keys of arrays in PHP can be strings, and the values ​​can be of any type.

In PHP, there are three types of arrays:

● Numeric array - an array with a numeric ID key

● Association Array - an array with specified keys, each key is associated with a value

● Multidimensional array - an array containing one or more arrays

Then PHP array keys are case-sensitive No?

Array index (key name) is case-sensitive

<?php
$arr = array(&#39;one&#39;=>&#39;first&#39;);
echo $arr[&#39;one&#39;];    //输出&#39;first&#39;
echo $arr[&#39;One&#39;];    //无输出并报错
echo $Arr[&#39;one&#39;];    //上面讲过，变量名区分大小写，所以无输出并报错
?

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