PHP 5: Extracto de libro para certificacón PHP ( Zend PHP 5)

aca el libro completo
http://rapidshare.com/files/355753489/Zend_PHP_5_Certification_Study_Guide_Oct_2006.pdf.html
MD5: 7CB357EB7F081FCCD2FEC5514A44EF52

copio algunas cosas que me parecieron interesantes..

<?php
function hello()
{
    if (func_num_args() > 0) 
    {
        $arg = func_get_arg(0); // The first argument is at position 0
        echo "Hello $arg";
    } 
    else 
    {
        echo "Hello World";
    }
}

hello("Reader"); // Displays "Hello Reader"
hello(); // Displays "Hello World"
?>

borrar un elemento de un Array

<?php
//Finally, an element can be deleted froman array by unsetting it:
$a = array (’a’ => NULL, ’b’ => 2);
unset ($a[’b’]);
echo in_array ($a, 2); // False
?>

ordenar desordenar Arrays

<?php
$cards = array (1, 2, 3, 4);
//sort ($cards);
shuffle ($cards);
var_dump ($cards);

//Since the shuffle() function randomizes the order of the elements of the array, the
//result of this script will be different every time—but here’s an example:

array(9) {
[0]=>
int(4)
[1]=>
int(1)
[2]=>
int(2)
[3]=>
int(3)
}
?>

Seguridad

<?php
$clean = array();

if (ctype_alpha($_POST[’username’]))
{
$clean[’username’] = $_POST[’username’];
}

if (ctype_alnum($_POST[’password’]))
{
$clean[’password’] = $_POST[’password’];
}

$colours = array(’Red’, ’Blue’, ’Yellow’, ’Green’);
if (in_array($_POST[’colour’], $colours))
{
$clean[’colour’] = $_POST[’colour’];
}
?>

<?php
if ( ctype_alnum($_REQUEST['email']) && ctype_alnum($_REQUEST['pass']) )
{

}
else
{
    die("invalido.. <a href='index.php'>Volver</a>");
    // header("Location: index.php");
}
?>