Are php class names case sensitive?

PHP's handling of case-sensitive issues is messy, and problems may occasionally occur when writing code, so I'll summarize it here.

But I am not encouraging everyone to use these rules. It is recommended that everyone always adhere to "case sensitivity" and follow unified coding standards.

Variable names are case-sensitive (Recommended learning: PHP programming from entry to proficiency)

 <?php
 $abc = &#39;abcd&#39;;
 echo $abc; //输出 &#39;abcd&#39;
 echo $aBc; //无输出
 echo $ABC; //无输出

Constant names are case-sensitive by default and are usually written in uppercase

<?php
 define("ABC","Hello World");
 echo ABC; //输出 Hello World
 echo abc; //输出 abc

php.ini configuration item instructions are case-sensitive

such as file_uploads = 1 cannot be written as File_uploads = 1

Function names, method names, and class names are not case-sensitive

But it is recommended to use the same name as when defined

 <?php
 function show(){
 echo "Hello World";
 }

Magic constants are not case-sensitive, uppercase letters are recommended

Including: __LINE__, __FILE__, __DIR__, __FUNCTION__, __CLASS__, __METHOD__, __NAMESPACE__.

<?php
 echo __line__; //输出 2
 echo __LINE__; //输出 3

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