PHP Starter Pack

// Integer
$integer = 2;
$integer = '2'; // Also you can assign the variable to a completely different type

// Float
$float = 3.14;

// Boolean
$boolean = true; // It has two values: `true` and `false`

// String
$string = 'JoJo'; // You can also use double quotes for strings "JoJo"

// Array
$array = [1, 2, 3];
echo $array[1]; // Prints the second element in array: `2`
$array[0] = 0; // Changes element in index 0 to value 0, $array == [0, 2, 3]
$arrayWithDifferentTypes = [true, 'two', 3]; // Arrays can contain different value types

// Associative array
$associativeArray = ['one' => 1, 'two' => 2, 'three' => 3]; // In other languages they're also called maps or dictionaries
echo $associativeArray['one']; // This echos the value corresponding to key `one`;
$associativeArray['one'] = 'won'; // This change value of key `one` to value `won`

// Variables in PHP start with `$`
$isVar = true;
$canExecute = false;

if($isVar) {
    /* You can use `echo` to print something on browser page, It can even be HTML */
    echo '<p>Yes it\'s a variable!</p>';
} else if($canExecute) {
    // You can use `''` or `""` for strings
    echo "No it can\'t execute!";
} else {
    echo 'Just your typical else';
}

// PHP also supports ternary expression
$isTernary = true;
$answer = $isTernary ? 'Yes' : 'No';

$count = 0;

// A while loop
while($count < 3) {
    // You can insert variables inside strings by using their name, Note that in order for this to work you need to use double quotes("") around string
    echo "Count is $count";
    $count++;
}

// For loop
for($i = 0; $i < 3; $i++) {
    echo 'Count is ' . $i;
}

// Foreach loop using an array
$array = ['One', 'Two', 'Three'];
foreach($array as $num) {
    echo '$num is ' . $num;
}

$associativeArray = ['One' => 1, 'Two' => 2, 'Three' => 3];

// Foreach loop using an associative array
// Associative arrays are kinda like dictionaries/maps in other languages
foreach($associativeArray as $key => $value) {
    echo "$key is $value";
}

// Mathematical operators
// Supported operators: `+`, `-`, `*`, `/`, `%`
$math = 2 + 2;
// Supported operators: `+=`, `-=`, `*=`, `/=`, `%=`
$math *= 2;
// Supported operators: `$math++`, `++$math`, `$math--`, `--$math`
$math++;

// Comparison operators
// Supported operators: `===`, `==`, `>`, `<`, `>=`, `<=`, `!==`
$comparison = 2 === 2;
$comparison = 2 >= 3;

// Boolean operators
// Supported operators: `&&`, `||`, `!`
$boolean = true && false;

// Concatenation
$concatenation = 'Con' . 'cat' . 'ena' . 'tion';

// Reference operator: &
// Copy by value
$array = [1, 2, 3];
$arrayCopy = $array[1];
print("\$array before \$arrayCopy change: ");
print_r($array);
$arrayCopy = 5;
print('$array after $arrayCopy change: ');
print_r($array);
// Copy by reference
$arrayReference = &$array[1]; // <---
print('$array before $arrayReference change: ');
print_r($array);
$arrayReference = 5;
print('$array after $arrayReference change: ');
print_r($array);

// Casting
// Supported operators: `(int)`, `(bool)`, `(float)`, `(string)`, `(array)`, `(object)`, `(unset)`
$casting = (int) 3.14; // 3
$casting = (bool) 2; // true or 1

function multiply($x, $y) {
    return $x * $y;
}
echo '2 * 2 = ' . multiply(2, 2);

// Functions can have default values
$hello = function($name = 'ryakosh') {
    echo "Hello $name" . '!';
};
$hello();

// You can pass functions as arguments, They're also called callbacks
function multiplyThenDevideByTwo($multiplyFunc, $x, $y) {
    return ($multiplyFunc($x, $y)) / 2;
}
echo multiplyThenDevideByTwo(multiply, 2, 2);

class Animal {
    // This is an instance property, It can be accessed using `$this->$name` inside of Animal class or it's subclasses
    public $name;

    // Constructor
    public function __construct($name) {
        $this->name = $name;
    }

    public function eat($food) {
        return "($food) Naam Naam";
    }

    // By default methods without an access modifier are considered `public`
    function live($food) {
        echo $this->eat($food) . ' ' . $this->poop() . ' ' . $this->sleep();
    }
    
    protected function sleep() {
        return 'Zzzz';
    }

    private function poop() {
        return '💩';
    }
}

// Inheritance using PHP
class Dog extends Animal {
    protected function sleep() {
        return 'Zzzz(Shhhh! ' . $this->name . ' is sleeping)';
    }
}

// The `new` keyword is used for object creation from a class
$dogObject = new Dog('Shiba');
// Object properties can get access using `->`
$dogObject->live('Burger');
// New properties can be added to objects or you can change existing ones
$dogObject->color = 'black';


if($dogObject instanceof Dog) {
    echo 'Yes, $dogObject is an instace of Dog class';
}

function isEaNasir($name) {
    if($name === 'Ea-Nasir') {
        // You can throw exceptions in PHP
        throw new Exception('Do not buy copper ingots from Ea-Nasir');
    }
}

try {
    isEaNasir('Ea-Nasir'); // Exception will be thrown
    echo 'If you see this message your safe from shitty copper ingots';
} catch(Exception $e) {
    echo $e->getMessage();
}

// -------------------- String --------------------
$string = 'The quick brown fox';

print_r(explode(' ', $string)); // Spliting
echo strlen($string); // 19
echo trim($string, "Thefox"); // quick brown
echo chr(65);
echo ord('A');
echo strcmp('Equal?', $string); // 0 = equal, -1 = string 1 is less than string 2, +1 = string 1 is more than string 2
echo strrev($string);
echo strtolower($string);
echo strtoupper($string);
echo substr($string, 4, 5); // quick
printf('%s jumps over the lazy dog', $string);
echo '<br />';
// -------------------- String End --------------------

// -------------------- Array --------------------
$array = array(1, 2, 3);

echo count($array);
print_r(array_fill(0, 3, 0)); // From index 0 till index 2(Second argument is length not index) fill the array with `0`s
echo array_pop($array);
echo array_push($array, 3, 4);
echo array_rand($array); // Return a random element from array
print_r(array_reverse($array));
echo array_search(3, $array); // Search for an element and return it's corresponding key
echo array_sum($array);
shuffle($array);
print_r($array);
echo in_array(2, $array);

function isDivisible2($element) {
    return ($element % 2) === 0;
}
print_r(array_filter($array, 'isDivisible2')); // Note that `isDivisible2` callback is passed as a string

function multiply2($element) {
    return $element * 2;
}
print_r(array_map('multiply2', $array)); // Note that `multiply2` callback is passed as a string
echo '<br />';
// -------------------- Array End --------------------

// -------------------- Utility --------------------
echo empty($variable); // Is variable empty/null?

$variable = '3.14';
echo floatval($variable); // Convert to float
echo gettype($variable); // Get the type's name as string
echo intval($variable); // Convert to int
echo is_string($variable);
echo is_int($variable);
echo is_array($variable);
echo is_float($varialbe);
echo is_bool($variable);
echo is_object($variable);
echo is_null($variable);
echo isset($variable); // Is variable set and not null?
echo strval(3.14); // Convert to string
echo var_dump($variable); // Get information about the variable
echo '<br />';
// -------------------- Utility End --------------------

// -------------------- Date --------------------
$currentDataTime = date_create(); // Current date and time as `Datetime`
$currentDateTimeTimestamp = time(); // Current time as timestamp
$dateTime = date_create('2022-12-30'); // Create `Datetime` using a string value
$timestamp = mktime(0, 0, 0, 12, 30, 2022); // Create a timestamp using provided date and time
$formatedCurrentDateTime = date('h:i:s Y-m-d'); // Get the current date and time and then format it according to the format string provided
echo date_timestamp_get($dateTime);
echo '<br />';
// -------------------- Date End --------------------

// -------------------- Regular Expression --------------------
$regex = '/ar.+/i'; // In PHP regular expressions are strings with delimiters(Here `/` is used as delimiter) and optional modifiers passed after the closing delimiter
echo preg_match($regex, 'arya'); // If there is a match it returns 1 otherwise 0
echo preg_match_all($regex, 'arya aryan armita'); // Returns the number of times regex has been found in the provided string
echo preg_replace($regex, 'arya', 'aryan'); // Replace every occurrence of the regex with the string provided
// -------------------- Regular Expression End --------------------

// -------------------- File --------------------
include('path/to/file.php'); // Copy file.php PHP file contents in here and show a warning if it doesn't exist
require('path/to/file.php'); // Same as above but throws an error if file.php doesn't exist
echo readfile('path/to/file.txt'); // Return the entire contents of the file.txt as string
$file = fopen('path/to/file.txt', 'r');
echo fgets($file); // Read a line from the file
echo filesize('path/to/file.txt'); // Return file size in bytes
echo fread($read, 12); // Read the maximum 12 chars from the file
fclose($file);
$file = fopen('path/to/file.txt', 'a');
fwrite($file, 'Text to write');
// -------------------- File End --------------------