functions.php

<?php
    $title = "Funtions";
    include 'includes/header.php'; 
?>
    <h1><center>Functions</center></h1>   

    <?php

        /* Defining a Function */

        function writeMessage(){
            echo "You are really a nice person, Have a nice time!<br/>";
        }

        /* Calling a Function */

        writeMessage();

        echo '<hr>';

        writeMessage(); 

        /* Function  with parameters */

        function addFunction($num1, $num2){
            $num = $num1 + $num2;
            echo "The sum of $num1 and $num2 is: $num<br/>";
        }    
    
        /* Pass by Reference - use ampersend in parameter */
        function changeNum(&$num){
            $num = $num + 10;
            // $num+= 10;
        }

        function returnProduct($num1, $num2){
            $prod = $num1 * $num2;
            return $prod;
        }

        $num = 500;
        addFunction(10, 32);        
        addFunction(10, $num);
        addFunction('10', "50");

        changeNum($num);
        echo $num . '<br/>';

        $return_value = returnProduct(10, 200);
        echo $return_value   . '<br/>';
        echo '<hr>';

    ?>
    <?php require 'includes/footer.php' ?>