PHP Variables

In PHP every variable name begins with a dollar sign ($) followed by the name. You create a variable simply by assigning a value to it with the equals sign; there is no separate declaration step. From that moment the name holds the value until you change it or the script ends.

<?php
$name = "Aisha";      // a string
$age = 29;             // an integer
$height = 1.68;        // a float
$isMember = true;      // a boolean

echo $name . " is " . $age . " years old.";
?>

Naming rules

PHP is strict about how variable names are formed. Following these rules keeps your code valid and readable. Note that variable names are case-sensitive, so $total and $Total refer to two completely different variables.

• A name must start with a letter or an underscore, never a digit.
• After the first character it may contain letters, digits, and underscores.
• No spaces or special characters such as - or % are allowed.
• Names are case-sensitive: $count and $Count are distinct.

PHP is loosely typed

You do not tell PHP what kind of value a variable will hold; it works that out from the value you assign. You can even reassign a variable to a different type later, though doing so can make code harder to follow. Use the var_dump function when you want to see the exact type and value PHP is storing.

<?php
$data = 42;
var_dump($data);      // int(42)

$data = "forty-two";
var_dump($data);      // string(9) "forty-two"
?>