In One Video

Lesson 34
Author : 🦒
Last Updated : November, 2017

PHP Overview

Php is a server side scripting language, designed primarily for use on web servers, but also used as a general purpose programming language. Php was created in the 1990s by Rasmus Lerdorf, and is fully Object Oriented.

The most common use case for PHP is in web development. Because PHP can be written along side HTML, and also because it integrates so well with HTML and other web technologies, you’ll often find it running on a web server.

PHP began as a set of rudimentary C programs designed to help it’s founder maintain his website’s homepage. But soon snowballed into a fully fledged language by 1997.

How PHP is Run

Generally PHP code is run using an interpreter which sits on the web sever, once the PHP code is executed a finished webpage is then sent to the user. This process allows for the creation of dynamic web pages, meaning aspects of the website can change dynamically depending on the result of executing the PHP code.

The most popular PHP interpreter is completly free and can be deployed on most webservers and operating systems. Because it’s free and portable PHP has become a staple in the web development world.

PHP utilizes a garbage collector and it’s syntax is based on a C, C++ style.

Choosing an IDE

Many developers choose to write PHP using a basic text editor, generally PHP will be written in the same enviornment as the HTML and front end technologies that it interacts with. Although several special IDE’s have been developed, some of the most popular include NetBeans, PHP Storm and Adobe DreamWeaver.

Code

Printing

Copyecho "<h1>Hello World</h1>");
print "<hr/>";                           // returns 1
echo  "<p>This is a php tutorial</p>";

Variables and Data Types

Copy/*
Names are case-sensitive and must start with '$' then:
   letters, _
After, may include
   letters, numbers, _
Convention says
   Start with a lowercase word, then additional words are capitilized
   ex. myFirstVariable
*/
$name = "Mike";    // Strings
$age = 30;         // Integer
$gpa = 3.5;        // Decimal
$isTall = true;    // Boolean -> true/false

$name = "John";

echo  "Your name is $name <br>";

Casting and Converting

Copyecho ((int)3.14)."<br>";
echo ((float)3)."<br>";
echo ((int)"80" + (float)"60.5")."<br>";
echo  intval("80") + floatval("60.5");

Strings

Copy$greeting = "Hello";
//indexes:   01234

echo  strlen($greeting)."<br>";
echo  $greeting[0]."<br>";
echo  $greeting[-1]."<br>";
echo  str_replace("l", "Z", $greeting)."<br>";
echo  strchr($greeting, "ll")."<br>";

Numbers

Copyecho (2 * 3)."<br>";            // Basic Arithmetic: +, -, /, *
echo (2**3)."<br>";             // Basic Arithmetic: +, -, /, *
echo (10 % 3)."<br>";           // Modulus Op. : returns remainder of 10/3
echo (1 + 2 * 3)."<br>";        // order of operations
echo (10 / 3.0)."<br><br>";     // int's and doubles


$num = 10;
$num += 100;                    // +=, -=, /=, *=
echo $num."<br>";

$num++;
echo $num."<br><br>";

// useful math methods
echo max(2, 3)."<br>";
echo sqrt(144)."<br>";
echo round(2.7)."<br>";

User Input GET

Copy<form action="App.php" method="GET">
     Username: <input type="text" name="username">
</form>

<?php
echo $_GET["username"];
echo "</br>";
$age = $_GET["age"];
echo $age;
?>

User Input POST

Copy<form action="App.php" method="POST">
     Username: <input type="text" name="username">
</form>

<?php
echo $_POST["username"];
?>

Arrays

Copy// $lucky_numbers = [];
// $lucky_numbers = array(4, 8, "fifteen", 16, 23, 42.0);
$lucky_numbers = [4, 8, "fifteen", 16, 23, 42.0];
//      indexes  0  1       2      3   4   5

$lucky_numbers[0] = 90;
echo $lucky_numbers[0]."<br>";
echo $lucky_numbers[1]."<br>";
echo count($lucky_numbers)."<br>";

2 Dimensional Arrays

Copy$number_grid = [ [1, 2], [3, 4] ];
$number_grid[0][1] = 99;

echo $number_grid[0][0]."<br>";
echo $number_grid[0][1]."<br>";

Array Functions

Copy$friends = [];
array_push($friends, "Oscar", "Angela");
array_push($friends, "Kevin");

// array_pop($friends);
echo "$friends[0], $friends[1], $friends[2] <br>";
sort($friends);
echo "$friends[0], $friends[1], $friends[2] <br>";
echo in_array("Oscar", $friends);

Associative Arrays

Copytest_grades = {
    "Andy" => "B+",
    "Stanley" => "C",
    "Ryan" => "A",
    3 => 95.2
}
echo  test_grades["Andy"]."<br>";
echo  test_grades["Ryan"]."<br>";
echo  test_grades[3]."<br>";

Functions

Copyfunction addNumbers($num1, $num2=99){
     return $num1 + $num2;
}

$sum = addNumbers(4, 3);
echo $sum;

If Statements

Copy$isStudent = false;
$isSmart = false;

if($isStudent && $isSmart){
     echo "You are a student";
} elseif($isStudent && !$isSmart){
     echo "You are not a smart student";
} else {
     echo "You are not a student and not smart";
}
echo "<br>";

// >, <, >=, <=, !=, ==
if(1 > 3){
     echo "number comparison was true";
}
echo "<br>";

if("dog" == "cat"){
   echo "string comparison was true";
}

Switch Statements

Copy$myGrade = "A";
switch($myGrade){
     case "A":
          echo "You Pass";
          break;
     case "F":
          echo "You fail";
          break;
     default:
          echo "Invalid grade";
}

While Loops

Copy$index = 1;
while ($index <= 5){
     echo $index;
     $index += 1;
}

$index = 1;
do{
     echo $index;
     $index += 1;
}while ($index <= 5);

For Loops

Copyfor($i = 0; $i < 5; $i++){
     echo $i;
}

$luckyNums = [4, 8, 15, 16, 23, 42];
foreach($luckyNums as $luckyNum){
     echo $luckyNum."<br>";
}

Exception Catching

Copytry{
     throw new Exception('Something bad happened');
} catch(Exception $e){
     echo $e->getMessage();
} finally{
     echo "<br> This code gets executed no matter what";
}

Classes and Objects

Copyclass Book{
     var $title;
     public $author;
     public static $staticAttribute = "My Static Attribute";

     function readBook(){
          echo "Reading $this->title by $this->author";
     }
};


$book1 = new Book;
$book1->title = "Harry Potter";
$book1->author = "JK Rowling";

echo $book1->title."<br>";
echo Book::$staticAttribute."<br>";
$book1->readBook();

Constructors

Copyclass Book{
     var $title;
     public $author;

     function __construct($title, $author){
          $this->title = $title;
          $this->author = $author;
     }

     function readBook(){
          echo "Reading $this->title by $this->author";
     }
};


$book1 = new Book("Harry Potter", "JK Rowling");
// $book1->title = "Half-Blood Prince";

echo $book1->title."<br>";

Getters and Setters

Copyclass Book{
     private $title;
     public $author;

     function __construct($title, $author){
          $this->setTitle($title);
          $this->author = $author;
     }

     function getTitle(){
          return $this->title;
     }
     function setTitle($title){
          $this->title = $title;
     }

     function readBook(){
          echo "Reading $this->title by $this->author";
     }
};


$book1 = new Book("Harry Potter", "JK Rowling");
$book1->setTitle("Half-Blood Prince");

echo $book1->getTitle();

Inheritance

Copyclass Chef{

     public $name;
     public $age;

     function __construct($name, $age){
          $this->name = $name;
          $this->age = $age;
     }

     function makeChicken(){
          echo "The chef makes chicken";
     }
     function makeSalad(){
          echo "The chef makes salad";
     }
     function makeSpecialDish(){
          echo "The chef makes bbq ribs";
     }
};
class ItalianChef extends Chef{

     public $countryOfOrigin;

     function __construct($name, $age, $countryOfOrigin){
          $this->countryOfOrigin = $countryOfOrigin;
          parent::__construct($name, $age);
     }

     function makePasta(){
          echo "The chef makes pasta";
     }
     function makeSpecialDish(){
          echo "The chef makes chicken parm";
     }
};


$chef = new Chef("Gordon Ramsay", 50);
$chef->makeChicken();
echo "<br>";
$italianChef = new ItalianChef("Massimo Bottura", 55, "Italy");
$italianChef->makeChicken();
echo "<br> $italianChef->countryOfOrigin";

Abstract Classes and Methods

Copyabstract class Vehicle{
     public abstract function move();
     public function getDescription(){
          echo "Vehicles are used for transportation";
     }
}

class Bicycle extends Vehicle{
     public function move(){
          echo "The bicycle pedals forward";
     }
}

class Plane extends Vehicle{

     public function move(){
          echo "The plane flys through the sky";
     }
}


$plane = new Plane();
$plane->move();
echo "<br>";
$plane->getDescription();

Interface Inheritance

Copyinterface Animal{
     public function speak();
}

class Cat implements Animal{
     public function speak(){
          echo "Meow Meow <br>";
     }
}

class Dog implements Animal{
     public function speak(){
          echo "Woof Woof <br>";
     }
}


$animals = [
     new Dog(),
     new Cat()
];

foreach($animals as $animal){
     $animal->speak();
}