Summary of the issue of whether PHP is case sensitive

PHP is case sensitive for variables and constants. Class names and method names are not case-sensitive. It is not sensitive to null, false, true, etc., and is also sensitive to the configuration parameters in php.ini. This article summarizes the issues in this regard.

This article is a summary of whether PHP is case sensitive. However, it is recommended to always adhere to "case sensitivity" and follow unified coding standards. 1. Case sensitivity 1. Variable names are case-sensitive

<?php
/**
* 大小写敏感
* edit bbs.it-home.org
*/
$abc ='abcd';
echo $abc; //输出 'abcd'
echo $aBc; //无输出
echo $ABC; //无输出
?>

2. Constant names are case-sensitive by default and are usually written in uppercase. (But I couldn’t find a configuration item that can change this default, please solve it)

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

3, php.ini configuration item instructions are case sensitive For example, file_uploads = 1 cannot be written as File_uploads = 1

2. Case insensitive 1. Function names, method names, and class names are not case-sensitive, but it is recommended to use the same names as when they were defined. 2. Magic constants are not case-sensitive, uppercase is recommended Includes: __LINE__, __FILE__, __DIR__, __FUNCTION__, __CLASS__, __METHOD__, __NAMESPACE__.

<?php
echo __line__;  //输出 2
echo __LINE__;  //输出 3
//by bbs.it-home.org
?>

3. NULL, TRUE, and FALSE are not case-sensitive. The php function var_dump is used below.

<?php
$a =null;
$b =NULL;
  
$c =true;
$d =TRUE;
  
$e =false;
$f =FALSE;
  
var_dump($a ==$b);//输出 boolean true
var_dump($c ==$d);//输出 boolean true
var_dump($e ==$f);//输出 boolean true
//by bbs.it-home.org
?>