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PHP Certification - Sep 2022

Last Slide: http://localhost:8884/#/8/27

TODO

Homework

For Mon 10 Oct 2022

  • Mock Exam 2
  • Quizzes for Topics 8 to 11 (everything that's left)
  • Final Mock Exam

For Fri 07 Oct 2022

  • Mock Exam 2
  • Quizzes for Topic 7 (OOP)

For Mon 03 Oct 2022

  • Mock Exam 1
  • Quizzes for Topic 5 (I/O)
  • Quizzes for Topic 6 (Functions) For Fri 30 Sep 2022
  • Quizzes for Topic 2 (Formats and Types)
  • Quizzes for Topic 3 (Strings and Patterns)
  • Quizzes for Topic 4 (Arrays) For Wed 28 Sep 2022
  • Quizzes for Topic 1 (Basics)

Docker Container Setup

  • Download the ZIP file from the URL given by the instructor
  • Unzip into a new folder /path/to/zip
  • Follow the setup instructions in /path/to/zip/README.md

Class Notes

What is considered "empty"?

<?php
namespace abc {
        define('WHATEVER', 'Whatever', TRUE);
        const ANYTHING = 'Anything';
}

namespace xyz {
        echo WHATEVER;
        echo ANYTHING;
}

Bitwise Operators

Tutorial oriented towards the exam:

<?php
echo "Logical AND\n";
printf("%04b\n", 0b00 & 0b00);
printf("%04b\n", 0b00 & 0b01);
printf("%04b\n", 0b01 & 0b00);
printf("%04b\n", 0b01 & 0b01);

echo "Logical OR\n";
printf("%04b\n", 0b00 | 0b00);
printf("%04b\n", 0b00 | 0b01);
printf("%04b\n", 0b01 | 0b00);
printf("%04b\n", 0b01 | 0b01);

echo "Logical XOR\n";
printf("%04b\n", 0b00 ^ 0b00);
printf("%04b\n", 0b00 ^ 0b01);
printf("%04b\n", 0b01 ^ 0b00);
printf("%04b\n", 0b01 ^ 0b01);

Examples of the three ops:

<?php
$a = 0b11111111;
$b = 0b11011101;

printf("%08b", $a & $b); // 1101 1101
printf("%08b", $a | $b); // 1111 1111
printf("%08b", $a ^ $b); // 0010 0010

Left/right shift illustration:

<?php
echo 16 << 3;
echo "\n";
echo 0b10000000;
echo "\n";

echo 16 >> 3;
echo "\n";
echo 0b00000010;
echo "\n";

echo 15 >> 3;
echo "\n";
echo 0b00000001;
echo "\n";

Nested Ternary Construct

$a = 30;
$b = 20;
echo ($a < $b) ? 'Less' : (($a == $b) ? 'Equal' : 'Greater');
// output: "Greater"

Null coalesce operator example

$token = $_GET['token'] ?? $_POST['token'] ?? $_COOKIE['token'] ?? 'DEFAULT';

php.ini file settings:

Garbage Collection

Data Formats

Read up on SimpleXMLElement

<?php
// for relative formats see:
// https://www.php.net/manual/en/datetime.formats.relative.php
$date[] = new DateTime('third thursday of next month');
$date[] = new DateTime('now', new DateTimeZone('CET'));
$date[] = new DateTime('@' . time());
$date[] = (new DateTime())->add(new DateInterval('P3D'));
var_dump($date);

Strings

  • Study the docs on sprintf() to get format codes for that family of functions
  • Example using negative offsets:
<?php
$dir = '/home/doug/some/directory/';
if (substr($dir, 0, 1) === '/') echo 'Leading slash' . PHP_EOL;
if (substr($dir, -1) === '/') echo 'Trailing slash' . PHP_EOL;
if ($dir[-1] === '/') echo 'Trailing slash' . PHP_EOL;

<?php
$text = 'Doug Bierer';
$patt = '/(.*)\s(.*)/';
echo preg_replace($patt, '$2, $1', $text);
  • preg_replace() and preg_match() example using sub-patterns:
<?php
$string = 'April 15, 2003';
$pattern = '/(\w+) (\d+), (\d+)/i';
$replacement = '$2 $1 $3';
echo preg_replace($pattern, $replacement, $string);

preg_match($pattern, $string, $matches);
var_dump($matches);
  • Same thing, but going from European date format to American
<?php
$str = '5 April 2022';
$pat = '/^(\d+?) (\w+?) (\d{4})$/';
$rep = '$2 $1, $3';
echo preg_replace($pat, $rep, $str);
echo PHP_EOL;

Greediness Example:

<?php
$str = '<p>Para 1</p><p>Para 2</p><p>Para 3</p>';
// $pat = '!<p>.*</p>!';	// returns the entire string
$pat = '!<p>.*?</p>!';	// returns "<p>Para 1</p>"
preg_match($pat, $str, $matches);
var_dump($matches);
echo PHP_EOL;

Arrays

For iterating through an array beginning-to-end don't forget about these functions:

  • array_walk()
  • array_walk_recursive()
  • array_map() Also: please don't forget the array navigation functions:
  • reset(): sets pointer to top
  • end() : sets pointer to end
  • prev() : advances array pointer
  • next() : un-advances array pointer
  • key() : returns index value at array pointer
  • current() : returns value of element at array pointer

I/O

Streams

  • Don't have to study all functions, just certain of the more common ones
  • https://www.php.net/streams
    • stream_context_create()
    • stream_wrapper_register()
    • stream_filter_register()
    • stream_filter_append()
    • stream_socket_client() In addition to the informational file functions mentioned, you also have:
  • fileatime()
  • filemtime()
  • filectime() etc.

Functions

OOP

  • Read up on magic methods!
  • Iteration
    • Lookup these interfaces and understand what they do
      • Traversable
      • Both of the interfaces mentioned extend this interface
      • Iterator
        • Introduced earlier
        • Requires hard-coded iteration methods
      • IteratorAggregate
        • Passes the buck
        • Don't have to hard code iteration methods
  • Late static binding
  • Serialization example:
<?php
class Test
{
        public $a = 0;
        public $b = 0;
    public $c = 'Test';
    public $d = [];
    public $e = '';
        public function __construct(int $a, float $b, string $c, array $d)
        {
                $this->a = $a;
                $this->b = $b;
                $this->c = $c;
                $this->d = $d;
                $this->e = md5(rand(1111,9999));
        }
        public function __sleep()
        {
                return ['a','b','c','d'];
        }
        public function __wakeup()
        {
                $this->e = md5(rand(1111,9999));
        }
}
$test = new Test(222, 3.456, 'TEST', [1,2,3]);
var_dump($test);
$str = serialize($test);
echo $str . PHP_EOL;

$obj = unserialize($str);
var_dump($obj);

Database Topic

Fetch Modes:

  • Focus on array and object fetch modes

Security Topic

Questions are drawn from here:

Web Features

Make sure you're up on the php.ini settings pertaining to web features URL: https://www.php.net/manual/en/ini.list.php

  • variables_order
  • request_order
  • memory_limit
  • post_max_size
  • upload_max_filesize
  • file_uploads
  • max_file_uploads

Error Handling

Example of aggregated Catch block:

try {
    $pdo = new PDO($params);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException | Exception $e) {
    error_log('Database error: ' . date('Y-m-d H:i:s'));
} catch (Throwable $e) {
    error_log('Any and all errors or exceptions: ' . date('Y-m-d H:i:s'));
} finally {
    echo 'Database connection ';
    echo ($pdo) ? 'succeeded' : 'failed';
}

Change Request

Example of making object callable:

<?php
$sum = new class () {
    public $num = 0;
    public function __invoke($val) {
        $this->num += $val;
    }
};

$a = [1, 2, 3, 4, 5, 6, 7, 8];
array_walk($a, $sum);
echo 'Sum of Digits: ' . $sum->num;
// output: 36

Error

Resources

Mock Exam 2

Question 3 is wrong. Number s/be "999.000.000,00" Question 12 s/be "Which OF these files related ..."

Change Request for Code Repo

php_cert Repo for Class Demo