Data Types

In any programming language, data type describes the kind of value that can be stored in a variable and also the type of operations that can be performed on it. PHP supports ten primitive data types which are described as under:

Scalar Data Types

These are the predefined data types which can hold only a single value.

1. Boolean: This can hold only two values i.e. TRUE or FALSE. It is most commonly used with conditional statements.

<?php
     if(TRUE){
          print(“Statements for TRUE”);
     }
     if(FALSE){
          print (“Statements for FALSE”);
     }
?>

Test Yourself

2. Integer: Integer is a non-decimal number. Rules for declaring integer data type are as :

must have at least one digit.
must not contain any decimal point.
Integers can be specified in decimal, hexadecimal, octal or binary notation
It can range from -2,147,483,648 and 2,147,483,647.

<?php
     $num = 201;
     var_dump($num);

     //  ---output---
     //     int(201)

?>

Test Yourself

3. Float: Float is a decimal number or a number in an exponential form.

<?php
     $num_float = 201.986;
     var_dump($num_float);

     //    -----output----
     //     float(201.986)

?>

Test Yourself

4. String: String is a sequence of characters. It can be represented as a text in quotes. Quotes can be single or double.

<?php
     $str = ”Hello”;
     var_dump($str);

//     --- output ---
//     string(5) "Hello"

?>

Test Yourself

Compund Data Types

These are the predefined data types which can hold only a single value.

Array: An array is a sequential collection of elements stored in a single variable.

<?php
     $days = array("Sunday", "Monday", "Tuesday");
     var_dump($days);


/*
OUTPUT
     array(3) { 
          [0]=> string(6) "Sunday" 
          [1]=> string(6) "Monday" 
          [2]=> string(7) "Tuesday" 
     }
*/
?>

Test Yourself

2. Object: Objects have their own states and behaviours. An object is an instance of a class whereas a class is a blueprint which describes the state and behaviour that belongs to a particular object.

If you consider a human , state will be : name, age, height, weight etc.

behaviour will be : walking, laughing, sleeping etc.

On creating a __construct() function, PHP will automatically call this function when you create an object of the related class.

<?php
     class Person{
          public $name;
          public $age;
          public function __construct($name, $age) {
               $this->name = $name;
               $this->age = $age;
          }
          public function output() {
               echo "Name  ->  " . $this->name ;
               echo "<br>Age ->  " . $this->age ;
          }
     }

     $obj = new Person("Smith", 24);
     $obj -> output();
     echo "<br>";
     $obj = new Person("John", 30);
     $obj -> output();

/*
---OUTPUT---
Name -> Smith
Age -> 24
Name -> John
Age -> 30 
*/
?>

Test Yourself

3. Callable: Callable keyword is used to pass a function argument as a reference to a function.

A callable can be any one of the following :

an anonymous method.
a string having the name of the method.
an array describing an object method or a static class method.

<?php
     function callable_method(callable $format_type, $str) {
          echo $format_type($str)." <br>";
     }

     class demoClass{
          public static function static_method($arg) {
               return $arg . " !";
          }
          public function object_method($arg) {
               return "[$arg]";
          }
     }
     $res = function($str) {
          return substr($str, 0, 5);
     };
	 
     callable_method($res , "Good Morning");      // anonymous method
     callable_method("strtoupper", "Good Morning");      // string having method name
     callable_method(["demoClass", "static_method"], "Good Morning");  // static class  // method
     $object = new demoClass();  // Object method
     callable_method([$object, "object_method"], "Good Morning");

/*
---OUTPUT---
                        Good
                        GOOD MORNING
                        Good Morning !
                        [Good Morning]
*/
?>

Test Yourself

4. Iterable: Iterable is a pseudo-type which was introduced in PHP 7.1. It accepts an array or an object which is further iterable through foreach statement. The iterable keyword can be used as an argument or as a return type of the function.

<?php
     function iterable_method(iterable $iterable_var) {
          foreach($iterable_var as $val) {
               echo $val." <br> ";
          }
     }
     $arr = ["sunday", "monday", "tuesday"];
     iterable_method($arr);


/*
                    ---OUTPUT---
                        sunday
                        monday
                        tuesday
*/
?>

Test Yourself

Special Data Types

Null and Resource are two special data types.

Null: This data type has only one value i.e. NULL. If any variable is created without a value, it is automatically assigned with NULL value.

<?php
     $var = "Hello";
     $var = null;
     var_dump($var);


/*

---output will be---
NULL

*/
?>

Test Yourself

2. Resource: This data type refers to an external resource. Resource variable acts as a reference to an external source of data such as stream, file etc. The function is_resource() can be used to determine if a variable is a resource and get_resource_type() will return the type of resource it is. Various types of resources are handled in PHP and some selected ones are listed below:

RESOURCE TYPE NAME	CREATED BY	DESTROYED BY	DEFINITION
AddressInfo	socket_addrinfo_lookup()	None	AddressInfo (sockets extension)
bzip2	bzopen()	bzclose()	bzip2 file
curl	curl_copy_handle(), curl_init()	curl_close()	cURL handle
dbase	dbase_open()	dbase_close()	Link to Dbase database
ftp	ftp_connect(), ftp_ssl_connect()	ftp_close()	FTP stream
imap	imap_open()	imap_close()	Link to IMAP, POP3 server
mysql link	mysql_connect()	mysql_close()	Link to MySQL database
mysql result	mysql_db_query(), mysql_query()	mysql_free_result()	MySQL result
odbc link	odbc_connect()	odbc_close()	Link to ODBC database
Socket	socket_accept(),socket_create()	socket_close()	Socket (sockets extension)
stream	opendir()	closedir()	Dir handle
stream	fopen(), tmpfile()	fclose()	File handle
xml	xml_parser_create(), xml_parser_create_ns()	xml_parser_free()	XML parser
zlib	gzopen()	gzclose()	gz-compressed file

<?php
     $file = fopen("file.txt", "w");
     echo get_resource_type($file) . "\n";


/*

---  output: ---
stream

*/
?>

Test Yourself

Help Us to Improve our content

Let's Talk

Data Types

Scalar Data Types

Compund Data Types

Special Data Types

Help Us to Improve our content

Important Links

Company

Others

Explore

Data Types

Scalar Data Types

Compund Data Types

Special Data Types

Help Us to Improve our content

Important Links

Follow us on social :

Company

Others

Explore

Subscribe to Our News Letter!

Follow us on social :