Table of Contents
Data type and variable in PHP
Data type defines what type of value a variable can store.
In programming language, a variable is a value that can change.
PHP is a dynamically typed language. In dynamically typed language it is not required to specify the type of a variable because the type will be set at runtime.
To declare a variable in PHP we need to know the following things:
- The variable begins with the $ symbol followed by a name of the variable.
- The variable name is case-sensitive ($name and $NAME will be considered two different variables).
- A variable name does start with a number and only contains alpha-numeric characters(a-z, 0-9) and underscores (_)
Built-in data types in PHP
PHP supports the following built-in data types:
null, bool, int, float, string, array, object, resource
Now we will try to understand different php data types one by one with examples.
null data type
null data type overview
null data type has only one value – null. This is case-insensitive.
Example of using null data type
An example of null is:
<?php
$nullVal = null; // Or, NULL
?>bool data type
bool data type overview
bool data type only has two values – true or false. This is case-insensitive.
Example of using bool data type
An example of bool is:
<?php
$boolVal = true; // Or TRUE
?>int data type
int data type overview
An int is a number which may be positive or negative and should not have a decimal point(i.e. should be a whole number).
Example of using int data type
Example of int is:
<?php
$intVal = 2;
$intVal = -2;
?>float data type
float data type overview
A float is a number and should have a decimal point (must be a fractional number).
Example of using float data type
An example of float is:
<?php
$floatVal = 2.2;
?>string data type
string data type overview
A string is a collection of characters (character is equivalent to a byte).
Example of using string data type
An example of string is:
<?php
$stringVal = 'blue';
?>array data type
array data type overview
An array stores a number of values in one single variable.
Example of using array data type
An example of an array is:
<?php
$arrayVal = ['blue', 'green', 'red'];
?>object data type
object data type overview
An object is an instance of a class. A class is a collection of its constants, variables or properties, and functions or methods. To create an object new keyword is used.
Example of using object data type
The easiest way to instantiate an empty object is:
<?php
$emptyObject = new stdClass();
?>resource data type
resource data type overview
A resource holds references to external resources. Special functions are used to create and use resources.
Example of using resource data type
A database call is a common example of using the resource data type.