Post-3 (PHP) Declare Variables in PHP

# Creating (Declaring) Variables in PHP

• Example: 7

<?php

$txt = "Hi Netwax Lab!";

$x = 5;

$y = 10.5;

echo $txt;

echo "<br>";

echo $x;

echo "<br>";

echo $y;

?>

Output

Hi Netwax Lab!

5

10.5

# How to Output Text and a Variable

• Example: 8

<?php

$txt = "Hi Netwax Lab!";

echo "Hey $txt!";

?>

Output

Hey Hi Netwax Lab!!

• Example: 9

<?php

$txt = "Hi Netwax Lab!";

echo "Hey " . $txt . "!"

?>

Output

Hey Hi Netwax Lab!!

• Example: 10

<?php

$a = 10;

$b = 15;

echo $a+$b;

?>

Output

25

PHP has three different variable scopes:

1. Local
2. Global
3. Static

# Global and Local Scope

Define variable global still not use in inside function

• Example: 11

<?php

$a = 10; // variable global scope

function First() {

// using a inside this function will generate an error

echo "<p>Variable a inside function is: $a</p>";

}

First();

echo "<p>Variable a outside function is: $a</p>";

?>

Output

• Example: 12

<?php

function First() {

$a = 10; // variable local scope

// using a outside this function will generate an error

echo "<p>Variable a inside function is: $a</p>";

}

First();

echo "<p>Variable a outside function is: $a</p>";

?>

Output

• Example: 13

<?php

$a = 10; // variable global scope

function First() {

global $a;

echo "<p>Variable an inside function is: $a</p>";

}

First();

echo "<p>Variable an outside function is: $a</p>";

?>

<?php

$a = 10; // variable global scope

function First() {

global $a;

echo "<p>Variable an inside function is: $a</p>";

}

First();

echo "<p>Variable an outside function is: $a</p>";

?>

Output

Variable an inside function is: 10

Variable an outside function is: 10

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.

• Example: 14

<?php

$a = 10; // variable global scope

function First() {

$GLOBALS['a'] = $GLOBALS['a'] + $GLOBALS['a'];

}

First();

echo "<p>Variable an outside function is: $a</p>";

?>

Output

Variable an outside function is: 20

# Static Keyword

When a function is completed/executed, all of its variables are deleted. However, sometimes we want a local variable NOT to be deleted. We need it for a further job.

• Example: 15

<?php

function First() {

static $a = 0;

echo $a.'<br>';

$a++;

}

First();

First();

First();

?>

Output

0

1

2

----

@NetwaxLab