PHP Variables

Variables store data that your program can use and change. In PHP, every variable name starts with a dollar sign $.

Declaring variables

You create a variable simply by assigning a value to it.

<?php
$name = "Alice";
$age = 30;
$price = 9.99;

Dynamic typing

PHP decides the type automatically based on the value. The same variable can hold different types over time.

<?php
$data = "text";  // string
$data = 42;       // now an integer

Naming rules

• Must start with $ followed by a letter or underscore.
• Can contain letters, numbers, and underscores.
• Cannot start with a number.
• Names are case sensitive.

<?php
$user_name = "valid";
$_count = "valid";
// $2cool would be invalid

Basic scope

A variable created inside a function is local to that function. A variable outside is global and not visible inside functions by default.

<?php
$message = "outside";

function show() {
    // $message is not available here
    $local = "inside";
    echo $local;
}
show();