What characters cannot be included in php variable names?

php variables are "containers" used to store information. PHP variables can be assigned values ​​or expressions. So, how should PHP variables be named? What characters cannot be included in php variable names? Let's take a look at the naming rules of PHP variables.

Let’s look at an example first:

<?php
$x=5;
$y=6;
$z=$x+$y;
echo $z;
?>

Similar to algebra, you can assign a certain value (x=5) or an expression (z= x y).

Variables can have very short names (such as x and y) or more descriptive names (such as age, carname, totalvolume).

PHP variable naming rules:

● Variables start with a $ symbol, followed by the name of the variable

● Variable names must start with letters or underscore characters Start

● Variable names can only contain letters, numeric characters, and underscores (A-z, 0-9, and _ )

● Variable names cannot contain spaces, punctuation marks, and special characters

● Variable names are case-sensitive ($y and $Y are two different variables)

PHP variable naming rules and other notes

1. When naming a variable with two or more words, you can capitalize the first letter of all but the first word. Such as $myName, $yourFamilyName.

2. Variables named starting with underscore _ usually represent special variables. Such as creating protected attributes, PHP predefined variables ($_GET), global arrays, etc. in the class.

3. When defining variables, do not be greedy for brevity. Instead, use descriptive names to define variables.

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