Php

PHP

Server side programming language
LAMP model

Hello World

<!DOCTYPE html>
<meta charset=utf-8>
<title>PHP Test</title>
<?php
 echo 'Hello World';
?>

Every block of PHP code must start with <?php and end with ?> (or <? and ?>)
You need to place a semi-colon (;) at the end of each line of PHP code.
variable names must start with a dollar sign ($).
Try to build this in a index.php

pros

widely supported (php.net)
frameworks (Zend, CodeIgniter, CakePHP etc)
easy to learn
copy paste
Object Oriented Programming
Supports anything from database managing to image modification

cons

too easy -> not safe (SQL / BASH injection)
easy to write bad spagetti code
messy, inconsistent language
not so widely used for applications

to view the error logs:

cat /var/log/apache2/error.log

or run the file

php index.php

Mixing with HTML

<?php 
 // this is a PHP comment
$myHeader = "Header made with echo";
echo "<h3>".$myHeader."</h3>";
?>

<!--  Is similar to (note HTML comment)  -->
<?php $myHeader2 = "Header made with with HTML"; ?>
<h3> <?php echo $myHeader2; ?> </h3>

you can insert any amount of php blocks in a HTML page
and switch between HTML and PHP

Function syntax

function myFunction() { //declares a function, this is named myFunction
 return 'John Doe'; //returns the value 'John Doe'
}

echo 'My name is ' . myFunction() . '!'; 

//outputs the text concatenated with the return value of myFunction.
//myFunction is called as a result of this syntax.
//The result of the output will be 'My name is John Doe!'

function FunctionName (Arguments){ echo 'test'; }

Weirdness of PHP

<?php
if("foo" == TRUE){
	echo 'YES! foo == TRUE, because it is? Well okay....';
}

if("foo" == 0){
	echo 'Huh? "foo" is also a number?';
}

if(TRUE == 0){
	echo 'therefor True is also 0, right?! ';
}else{
	echo "WRONG!";
}

?>

A simple PHP portfolio page

<html>

<head>
    <style>
    #menu{
        border:1px solid black; 
        float:left; 
        width:200px;
        padding:10px;
    }
    #content{
        border:1px solid black; 
        float:left;
        width:600px;
        padding:10px;
    }
    #content img{width:100%;height:auto;}
    </style>
</head>

<body>

    <div id='menu'>
        <h2>Menu</h2>

        <?php
            echo '<h3>here we see the project names</h3>';
            $directoryName = 'content/';

            //check if it can open the directory
            if ($openDirectory = opendir($directoryName)) {
                // read each file/directory within
                while (($file = readdir($openDirectory)) !== false) {
                    // skip other paths
                    if ($file == '.' or $file == '..') continue;
                    // ?page= !!!!!! 
                    // notice the dot as concat
                    echo "<a href='index.php?page=".$file."'>".$file."</a><br/>";
                }
                closedir($openDirectory);
            }
            
        ?>
    </div>

    <div id='content'>
       <?php


        // GET the php variable from the url!!
        // GET looks at our current URL, and retrieves variables
        // http://pzwart3.wdka.hro.nl/~tklok/portfolio/index.php?folder=burgers
        // $_GET['folder'] => burger
     
        $dir_path = $directoryName . $_GET["folder"].'/';
        // check if it can open the directory

        if ($dir_handler = opendir($dir_path)) {
            // read each file/directory within
            $counter=0;
            while (($file = readdir($dir_handler)) !== false) {

                // skip other paths
                if ($file == '.' or $file == '..') continue;
                // only JPGs for now so....
                // check on the extention
                //
                $extention = substr(strrchr($file,'.'),1);
                if ($extention =='jpg'){
                    echo '<img class="jpg" id="img'.$counter. '" src="'.$dir_path.$file.'" />';
                }
                if ($extention == 'txt'){
                    //echo $dir_path.$file;
                    $filetext= file_get_contents($dir_path.$file);
                    echo $filetext;
                }
            $counter+=1;
            }
        closedir($dir_handler);
        }
    ?>
    </div>

</body>

</html>