What is Variables in PHP?

A variable is just a "container" area where we store the information (Like string or integer or or arrays value). PHP automatically convert Variables data types according its value.

<?php
$text = "strings variable";
$number = 5;
?>

Note:

Variable names should be case-sensitive, and In PHP variables are denoted with ($) dollar.
A variable name can not start with a number (means only contain alpha-numeric characters and underscores).
A variable name can not contain spaces.

What is Constants Variable in PHP?

A constant Variable can't change at execution time.
Constant Variable is defined using define() function,which accepts two arguments: the name of the constant, and its value.

<?php
    // Defining constants
    define("SITE_URL", "https://phplanguagecode.blogspot.com/");


    // Using constants
    echo "Visit my website ".SITE_URL;
    ?>
if you use SITE_URL any where then its show full url.

What is Variable References?

PHP also allows to create aliases or reference for variables, means a aliases is a variable, that assigned to or refer to the same information as another variable.

<?php
$a = 'nice day!';
$b = &$a;
$b = "Have a $b";
?>

Super global Variables.

PHP has several predefined variables these are called Super Globals. The PHP superglobal variables are:

$GLOBALS
$_SESSION
$_SERVER
$_COOKIE
$_GET
$_POST
$_REQUEST
$_FILES
$_ENV

PHP $_SERVER

which holds information about headers, paths, and script locations.
<?php
echo $_SERVER['SERVER_NAME'];
echo $_SERVER['PHP_SELF'];
echo $_SERVER['HTTP_HOST'];
?>

PHP $_REQUEST

collect data after submitting a form by GET or POST Method.

PHP $GLOBALS

for access global variables from anywhere in the PHP . it stores all variables in an array called $GLOBALS[index]. The index holds the name of the variable. example
<?php
$a = 5;
$b = 7;

function addition() {
$GLOBALS['c'] = $GLOBALS['a'] + $GLOBALS['b'];
}
addition();
echo $c;
?>

PHP Tutorials for Beginners

Monday, 30 May 2016

PHP Variables