PHP Variables

Variables are "containers" for storing information.

Creating (Declaring) PHP Variables

In PHP, a variable starts with the $ sign, followed by the name of the variable:

$x = 5;
$y = "John";

In the example above, the variable $x will hold the value 5, and the variable $y will hold the value "John".

Note: When you assign a text value to a variable, put quotes around the value.

Note: Unlike other programming languages, PHP has no command for declaring a variable. It is created the moment you first assign a value to it.

PHP Variables

A variable can have a short name (like $x and $y) or a more descriptive name ($age, $carname, $total_volume).

Rules for PHP variables:

• A variable starts with the $ sign, followed by the name of the variable
• A variable name must start with a letter or the underscore character
• A variable name cannot start with a number
• A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
• Variable names are case-sensitive ($age and $AGE are two different variables)

Output Variables

The PHP echo statement is often used to output data to the screen.

The following example will show how to output text and a variable:

$txt = "W3Schools.com";
echo "I love $txt!";

The following example will produce the same output as the example above:

$txt = "W3Schools.com";
echo "I love " . $txt . "!";

The following example will output the sum of two variables:

$x = 5;
$y = 4;
echo $x + $y;

Note: You will learn more about the echo statement and how to output data to the screen in the PHP Echo/Print chapter.

PHP is a Loosely Typed Language

In the example above, notice that we did not have to tell PHP which data type the variable is.

PHP automatically associates a data type to the variable, depending on its value. Since the data types are not set in a strict sense, you can do things like adding a string to an integer without causing an error.

In PHP 7, type declarations were added. This gives an option to specify the data type expected when declaring a function, and by enabling the strict requirement, it will throw a "Fatal Error" on a type mismatch.

You will learn more about strict and non-strict requirements, and data type declarations in the PHP Functions chapter.

Variable Types

PHP has no command for declaring a variable, and the data type depends on the value of the variable.

$x = 5;      // $x is an integer
$y = "John"; // $y is a string
echo $x;
echo $y;

PHP supports the following data types:

• String
• Integer
• Float (floating point numbers - also called double)
• Boolean
• Array
• Object
• NULL
• Resource

Get the Type

To get the data type of a variable, use the var_dump() function.

$x = 5;
var_dump($x);

var_dump(5);
var_dump("John");
var_dump(3.14);
var_dump(true);
var_dump([2, 3, 56]);
var_dump(NULL);

Assign String to a Variable

Assigning a string to a variable is done with the variable name followed by an equal sign and the string:

$x = "John";
echo $x;

String variables can be declared either by using double or single quotes, but you should be aware of the differences. Learn more about the differences in the PHP Strings chapter.

Assign Multiple Values

You can assign the same value to multiple variables in one line:

$x = $y = $z = "Fruit";