PHP case sensitive rules [reprinted]

PHP is not case sensitive. We recommend that you always stick to "Case sensitivity ". Note that classes and functions are case-insensitive. However, even if you are negligent, the interpreter will catch this error during debugging.

I. Case sensitivity 1. Variable names are case sensitive

All variables are case sensitive, including common variables and $ _ Get, $ _ post, $ _ Request, $ _ cookie, $ _ session, $ globals, $ _ server, $ _ files, $ _ ENV, etc;

2. Constant names are case-sensitive by default and are generally written in uppercase.

 

3. The php. ini configuration item command is case sensitive.

For example, file_uploads = 1 cannot be written as file_uploads = 1

Ii. Case Insensitive 1. The function name, method name, and class name are case insensitive, but the same name as the definition is recommended 2. The magic constant is case insensitive and it is recommended to use uppercase letters.

Including: __line _, _ file _, _ DIR _, _ function _, _ class _, _ method _, and _ namespace __.

3. null, true, and false are case-insensitive. 4. Type forced conversion, case-insensitive.

Including

• (INT), (integer)-convert to integer
• (Bool), (Boolean)-convert to boolean
• (Float), (double), (real)-convert to floating point type
• (String)-convert to string
• (Array)-convert to an array
• (Object)-convert to object