Introduction to php variables echo & print statements data types constants artihmetic & assigment operators comparison operators increment / decrement & logical operators string operators conditionals loops functions arrays strings superglobals date & time file handling cookies sessions error handling exceptions includes

1. #BURNINGKEYBOARDS
DENIS.RISTIC@PERPETUUM.HR

2. INTRODUCTION TO
PHP

3. INTRODUCTION TO PHP
PHP SYNTAX
▸ A PHP script starts with <?php and ends with ?> (not always)
▸ PHP statements end with a semicolon (;)
▸ Comments in PHP
// This is a single-line comment
# This is also a single-line comment
/*
This is a multiple-lines comment block
that spans over multiple lines
*/
▸ In PHP, all keywords (e.g. if, else, while, echo, etc.), classes, functions, and user-defined functions are
NOT case-sensitive
▸ However; all variable names ARE case-sensitive.
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4. INTRODUCTION TO PHP
PHP VARIABLES
▸ In PHP, a variable starts with the $ sign, followed by the name of the variable
▸ Rules for PHP variables:
▸ A variable starts with the $ sign, followed by the name of the variable
▸ A variable name must start with a letter or the underscore character
▸ A variable name cannot start with a number
▸ A variable name can only contain alpha-numeric characters and
underscores (A-z, 0-9, and _ )
▸ Variable names are case-sensitive ($age and $AGE are two different
variables)
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5. INTRODUCTION TO PHP
PHP VARIABLES
▸ PHP is a Loosely Typed Language
▸ The scope of a variable is the part of the script where the variable can be
referenced/used.
▸ PHP has three different variable scopes: local, global, static
▸ A variable declared outside a function has a global scope and can only be
accessed outside a function
▸ A variable declared within a function has a local scope and can only be accessed
within that function
▸ The global keyword is used to access a global variable from within a function
▸ Normally, when a function is completed/executed, all of its variables are deleted.
However, sometimes we want a local variable NOT to be deleted. To do this, use
the static keyword when you first declare the variable
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6. INTRODUCTION TO PHP
PHP ECHO AND PRINT STATEMENTS
▸ In PHP there are two basic ways to get output: echo and
print
▸ echo and print are more or less the same, they are both
used to output data to the screen
▸ The differences are small: echo has no return value while
print has a return value of 1 so it can be used in
expressions. echo can take multiple parameters (although
such usage is rare) while print can take one argument.
echo is marginally faster than print
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7. INTRODUCTION TO PHP
PHP EXAMPLE
<?php
echo "Hello World!";
$txt = "Hello world!";
$x = 5;
$y = 10.5;
echo "I love $txt!";
echo "I love " . $txt . "!";
echo "I love {$txt}!";
echo $x + $y;
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8. INTRODUCTION TO PHP
PHP EXAMPLE
<?php
function myTest() {
$x = 5; // local scope
echo "Variable x inside function is: $x";
}
myTest();
// using x outside the function will generate an error
echo "Variable x outside function is: $x";
$x = 5;
$y = 10;
function myTest() {
global $x, $y;
$y = $x + $y;
}
myTest();
echo $y; // outputs 15
function myTest() {
static $x = 0;
echo $x;
$x++;
}
myTest();
myTest();
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9. INTRODUCTION TO PHP
PHP DATA TYPES
▸ PHP supports the following data types:
▸ String
▸ Integer
▸ Float (floating point numbers - also called double)
▸ Boolean
▸ Array
▸ Object
▸ NULL
▸ Resource
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10. INTRODUCTION TO PHP
DATA TYPES EXAMPLE
<?php
$x = 'Hello world!';
echo $x;
$x = 5985;
var_dump($x);
$x = 10.365;
var_dump($x);
$x = true;
var_dump($x);
$cars = ["Volvo", "BMW", "Toyota"];
var_dump($cars);
class Car {
public $model;
function __construct($model) {
$this->model = $model;
}
}
$golf = new Car("WW");
echo $golf->model;
$x = null;
var_dump($x);
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11. INTRODUCTION TO PHP
PHP CONSTANTS
▸ A constant is an identifier (name) for a simple value. The
value cannot be changed during the script.
▸ A valid constant name starts with a letter or underscore (no
$ sign before the constant name).
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12. INTRODUCTION TO PHP
CONSTANTS EXAMPLE
<?php
define("SOMECONTANT", "burning keyboards”);
echo SOMECONSTANT; // outputs "burning keyboards"
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13. INTRODUCTION TO PHP
ARITHMETIC & ASSIGNMENT OPERATORS
<?php
$x = 10;
$y = 5;
echo $x + $y; // outputs 15
echo $x - $y; // outputs 5
echo $x * $y; // outputs 50
echo $x / $y; // outputs 2
echo $x % $y; // outputs 5
echo $x ** $y; // outputs 100000
$x += $y; // equal to $x = $x + $y
$x -= $y; // equal to $x = $x - $y
$x *= $y; // equal to $x = $x * $y
$x /= $y; // equal to $x = $x / $y
$x %= $y; // equal to $x = $x % $y
$x **= $y; // equal to $x = $x ** $y
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14. INTRODUCTION TO PHP
COMPARISON OPERATORS
<?php
$x = 10;
$y = 5;
$x == $y; // equal
$x === $y; // identical (equal + same type)
$x != $y; // not equal
$x !== $y; // not identical
$x <> $y; // not equal
$x > $y; // greater than
$x >= $y; // greater than or equal
$x < $y; // less than
$x <= $y; // less than or equal
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15. INTRODUCTION TO PHP
INCREMENT / DECREMENT & LOGICAL OPERATORS
<?php
++$x; // Pre-increment - increments $x by one, then returns $x
$x++; // Post-increment - returns $x, then increments $x by one
--$x; // Pre-decrement - decrements $x by one, then returns $x
$x--; // Post-decrement - returns $x, then decrements $x by one
$x && $y; // AND, returns true if both $x and $y are true
$x || $y; // OR, returns true if either $x or $y are true
$x xor $y; // XOR, returns true if either $x or $y is true, but not both
!$x; // NOT, returns true if $x is not true
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16. INTRODUCTION TO PHP
STRING OPERATORS
<?php
$str = $str1 . $str2; // concatenation
$str .= $str1; // concatenation assignment, appends $str2 to $str
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17. INTRODUCTION TO PHP
CONDITIONALS
<?php
$i = 11;
if ($i < 10) {
echo "Number is smaller than 10!";
} else if ($i < 20) {
echo "Number is smaller than 20!";
} else {
echo "Number is greater or equal to 20!";
}
$favoritecolor = "red";
switch ($favoritecolor) {
case "red":
echo "Your favorite color is red!";
break;
case "blue":
echo "Your favorite color is blue!";
break;
case "green":
echo "Your favorite color is green!";
break;
default:
echo "Your favorite color is neither red, blue, nor green!";
}
$a = ($b > $c) ? $b : $c;
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18. INTRODUCTION TO PHP
LOOPS
<?php
$x = 1;
while ($x <= 5) {
echo "The number is: $x";
$x++;
}
$x = 6;
do {
echo "The number is: $x";
$x++;
} while ($x <= 5); // this evaluates at the end, so it will always print once
for ($x = 0; $x <= 10; $x++) {
echo "The number is: $x";
}
$colors = ["red", "green", "blue", "yellow"];
foreach ($colors as $color) {
echo "$color <br>";
}
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19. INTRODUCTION TO PHP
FUNCTIONS
<?php
function writeMsg() {
echo "Hello world!";
}
writeMsg(); // call the function
function writeMsg($msq = "Default one") {
echo "My message: $msg";
}
writeMsg("New message");
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20. INTRODUCTION TO PHP
ARRAYS
<?php
$cars = ["BMW", "Mercedes", "Audi"];
echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . ".";
$cars_length = count($cars);
for ($x = 0; $x < $cars_length; $x++) {
echo $cars[$x];
}
$cars = [
"BMW" => "350d",
"Mercedes" => [
"E" => [220, 250, 300],
"S" => "500"
]
"Audi" => ["A8", "A6", "A4"]
];
echo "I like " . $cars['BMW'] . ".";
foreach ($cars as $key => $value) {
echo "Key: " . $key . ", Value: " . $value;
}
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21. INTRODUCTION TO PHP
STRINGS
<?php
echo strlen("Hello world!"); // outputs 12
echo strrev("Hello world!"); // outputs !dlrow olleH
echo strtoupper("Hello world!"); // outputs HELLO WORLD!
echo strpos("Hello world!", "world"); // outputs 6
echo str_replace("world", "Dolly", "Hello world!"); // outputs Hello Dolly!
var_dump(str_split("Hello world!")); // outputs ["H", "e", "l", "l", "o", " ", "w",
"o", "r", "l", "d", “!"]
var_dump(explode(" ", "Hello world!")); // outputs ["Hello", "world!"]
echo implode(" ", ["Hello", "world!"]); // outputs Hello world!
$number = 123;
printf("With 2 decimals: %1$.2f, With no decimals: %1$u", $number);
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22. INTRODUCTION TO PHP
SUPERGLOBALS
▸ Several predefined variables in PHP are "superglobals", which means that they are always
accessible, regardless of scope - and you can access them from any function, class or file
without having to do anything special.
▸ The PHP superglobal variables are:
▸ $GLOBALS
▸ $_SERVER
▸ $_REQUEST
▸ $_POST
▸ $_GET
▸ $_FILES
▸ $_ENV
▸ $_COOKIE
▸ $_SESSION
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23. INTRODUCTION TO PHP
DATE & TIME
<?php
echo "Today is " . date("d.m.Y H:i:s");
$d = mktime(11, 14, 54, 7, 5, 2017);
echo "Created date is " . date("Y-m-d h:i:sa", $d);
$d = strtotime("10:30pm July 5 2017");
echo "Created date is " . date("Y-m-d h:i:sa", $d);
$d = strtotime("tomorrow");
echo date("Y-m-d h:i:sa", $d);
$d = strtotime("next Saturday");
echo date("Y-m-d h:i:sa", $d);
$d = strtotime("+3 Months");
echo date("Y-m-d h:i:sa", $d);
$nextWeek = time() + (7 * 24 * 60 * 60); // + 7 days
echo 'Next Week: '. date('Y-m-d', $nextWeek);
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24. INTRODUCTION TO PHP
FILE HANDLING
<?php
echo readfile("some.txt");
$file = file_get_contents('some.txt'); // returns string
$homepage = file_get_contents('http://www.google.com/'); // returns string
$lines = file('some.txt');
foreach ($lines as $line_num => $line) {
echo "Line #{$line_num} : " . $line . "n";
}
$myfile = fopen("some.txt", "r") or die("Unable to open file!");
echo fread($myfile, filesize("some.txt"));
fclose($myfile);
$myfile = fopen("some.txt", "r") or die("Unable to open file!");
while (!feof($myfile)) {
echo fgets($myfile);
}
fclose($myfile);
$myfile = fopen("newfile.txt", "w") or die("Unable to open file!");
fwrite($myfile, "First linen");
fwrite($myfile, "Second linen");
fclose($myfile);
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25. INTRODUCTION TO PHP
COOKIES
<?php
setcookie("username", "John Doe", time() + (86400 * 30), "/"); // 86400 = 1 day
if (!isset($_COOKIE["username"])) {
echo "Cookie named username is not set!";
} else {
echo "Cookie username is set and has value " . $_COOKIE["username"];
}
// modify cookie
setcookie("username", "Jane Doe", time() + (86400 * 30), "/");
// delete cookie
setcookie("username", "", time() - 3600);
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26. INTRODUCTION TO PHP
SESSIONS
<?php
// Start the session
session_start();
// Set session variables
$_SESSION["username"] = "Jon Doe";
echo "Username is " . $_SESSION["username"];
// modify session
$_SESSION["username"] = "Jane Doe";
// delete single session variable
unset($_SESSION["username"]);
// remove all session variables
session_unset();
// destroy the session
session_destroy();
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27. INTRODUCTION TO PHP
ERROR HANDLING
<?php
if (!file_exists("welcome.txt")) {
die("File not found");
} else {
$file = fopen(“welcome.txt", "r");
}
function customError($errno, $errstr) {
echo "<b>Error:</b> [$errno] $errstr n";
}
set_error_handler("customError");
$test = 2;
if ($test >= 1) {
trigger_error("Value must be 1 or below");
}
error_log("You messed up!", 3, "/var/tmp/my-errors.log");
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28. INTRODUCTION TO PHP
EXCEPTIONS
<?php
function checkNum($number) {
if ($number>1) {
throw new Exception("Value must be 1 or below");
}
return true;
}
//trigger exception
checkNum(2);
try {
checkNum(2);
//If the exception is thrown, this text will not be shown
echo 'If you see this, the number is 1 or below';
} catch (Exception $e) {
echo 'Message: ' .$e->getMessage();
}
function myException($exception) {
echo "<b>Exception:</b> " . $exception->getMessage();
}
set_exception_handler('myException');
throw new Exception('Uncaught Exception occurred');
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29. INTRODUCTION TO PHP
INCLUDES
<?php
include 'header.php';
//include will only produce a warning (E_WARNING) and the script will continue
require 'body.php';
// require will produce a fatal error (E_COMPILE_ERROR) and stop the script
require_once 'footer.php';
// the require_once statement is identical to require except PHP will check if the file
has already been included, and if so, not include (require) it again.
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30. INTRODUCTION TO PHP
PHP REFERENCES
▸ PHP Manual
▸ http://php.net/manual/en/
▸ Zend PHP 101
▸ https://devzone.zend.com/6/php-101-php-for-the-absolute-
beginner/
▸ PHP The Right Way
▸ http://www.phptherightway.com/
▸ Awesome PHP
▸ https://github.com/ziadoz/awesome-php
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31. INTRODUCTION TO PHP
PHP REFERENCES
▸ PHP Best Practices
▸ https://phpbestpractices.org/
▸ PHP FIG
▸ http://www.php-fig.org/
▸ PHP Security
▸ http://phpsecurity.readthedocs.io/en/latest/index.html
▸ The PHP Benchmark
▸ http://phpbench.com/
▸ PHP Sandbox (Online)
▸ http://sandbox.onlinephpfunctions.com/
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