What are the rules for defining variables in php

In PHP, defining variables is one of the basic operations in programming. PHP editor Strawberry introduces to you the rules for defining variables in PHP: variable names must start with the $ symbol, followed by the variable name; variable names can only start with letters or underscores, and can be followed by letters, numbers, or underscores; case-sensitive , $name and $Name are different variables; variable names cannot contain spaces or special characters, and can only use letters, numbers, and underscores. Mastering these rules can better use PHP to define variables and improve programming efficiency.

1. Variable names must start with a dollar sign ($), followed by a letter or underscore, and then can be a combination of letters, numbers, or underscores. For example: $name, $_count.
2. Variable names are case-sensitive. For example: $name and $Name are different variables.
3. Variable names cannot start with numbers. For example: $1name is an invalid variable name.
4. Variable names cannot contain special characters, such as spaces, punctuation marks, and operators.
5. Variable names cannot use php reserved keywords, such as if, else, while, etc.
6. Variable names should use meaningful names to improve code readability and maintainability.
7. Variable names should avoid using abbreviations and abbreviations unless they are very clear in the context.
8. Variable names should try to use camel case naming or underline naming to improve readability. For example: $userName, $first_name.
9. Variable names can contain Unicode characters, but it is recommended to use only ASCII characters to ensure compatibility and readability.

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