PHP DATA TYPES
PHP data types are used to hold different types of data or values. PHP supports 8 primitive data types that can be categorized further in 3 types:
- Scalar Types
- Compound Types
- Special Types
PHP Data Types: Scalar Types
There are 4 scalar data types in PHP.
- boolean
- integer
- float
- string
PHP Data Types: Special Types
There are 2 special data types in PHP.
- resource
- NULL
PHP String
A string is a sequence of characters, like “Hello world!”.
A string can be any text inside quotes. You can use single or double quotes:
<?php $x = "Hello world!"; $y = 'Hello world!'; echo $x; echo "<br>"; echo $y; ?>
PHP Integer
An integer data type is a non-decimal number between -2,147,483,648 and 2,147,483,647.
Rules for integers:
- An integer must have at least one digit
- An integer must not have a decimal point
- An integer can be either positive or negative
- Integers can be specified in three formats: decimal (10-based), hexadecimal (16-based – prefixed with 0x) or octal (8-based – prefixed with 0)
In the following example $x is an integer. The PHP var_dump() function returns the data type and value:
<?php $x = 5985; var_dump($x); ?>
PHP Float
A float (floating point number) is a number with a decimal point or a number in exponential form.
In the following example $x is a float. The PHP var_dump() function returns the data type and value:
<?php $x = 10.365; var_dump($x); ?>
PHP Boolean
A Boolean represents two possible states: TRUE or FALSE.
$x = true; $y = false;
Booleans are often used in conditional testing.
PHP Array
An array stores multiple values in one single variable.
In the following example $cars is an array. The PHP var_dump() function returns the data type and value:
<?php $cars = array("Volvo","BMW","Toyota"); var_dump($cars); ?>
PHP Object
An object is a data type which stores data and information on how to process that data.
In PHP, an object must be explicitly declared.
<?php class Car { function Car() { $this->model = "VW"; } } // create an object $herbie = new Car(); // show object properties echo $herbie->model; ?>
PHP NULL Value
Null is a special data type which can have only one value: NULL.
A variable of data type NULL is a variable that has no value assigned to it.
Tip: If a variable is created without a value, it is automatically assigned a value of NULL.
Variables can also be emptied by setting the value to NULL:
<?php $x = "Hello world!"; $x = null; var_dump($x); ?>