PHP is a Loosely Typed Language

PHP is a Loosely Typed Language

PHP automatically converts the variable to the correct data type, depending on its value. In other languages such as C, C++, and Java, the programmer must declare the name and type of the variable before using it. PHP has three different variable scopes:

• local
• global
• static

Global and Local Scope

A variable declared outside a function has a GLOBAL SCOPE and can only be accessed outside a function:

Example
<?php
$x = 5; // global scope
function myTest()
{
    // using x inside this function will generate an error
    echo "<p>Variable x inside function is: $x</p>";
}
myTest();
echo "<p>Variable x outside function is: $x</p>";
?>

A variable declared within a function has a LOCAL SCOPE and can only be accessed within that function:

Example
<?php
function myTest()
 {
    $x = 5; // local scope
    echo "<p>Variable x inside function is: $x</p>";
}
myTest();
// using x outside the function will generate an error
echo "<p>Variable x outside function is: $x</p>";
?>

PHP The global Keyword
The global keyword is used to access a global variable from within a function. To do this, use the global keyword before the variables (inside the function):

Example
<?php
$x = 5;
$y = 10;
function myTest()
{
    global $x, $y;
    $y = $x + $y;
}
myTest();
echo $y; // outputs 15
?>

PHP also stores all global variables in an array called $GLOBALS[index]. The index holds the name of the variable. This array is also accessible from within functions and can be used to update global variables directly. The example above can be rewritten like this:

Example
<?php
$x = 5;
$y = 10;
function myTest()
{
    $GLOBALS['y'] = $GLOBALS['x'] + $GLOBALS['y'];
}
myTest();
echo $y; // outputs 15
?>

PHP The Static Keyword
use the static keyword when you first declare the variable.
Example
<?php
function myTest()
 {
    static $x = 0;
    echo $x;
    $x++;
}
myTest();
myTest();
myTest();
?>

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