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:
After the execution of the statements above, the variable
$txt will hold the value
Hello world!, the variable
$x will hold the value
5,
and the variable $y will hold the value
10.5.
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.
Think of variables as containers for storing data.
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 (
$ageand$AGEare two different variables)
Remember that PHP variable names are case-sensitive!
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:
The following example will produce the same output as the example above:
The following example will output the sum of two variables:
Note: You will learn more about the echo statement and how
to output data to the screen in the next 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.
