<?php
  echo "Hello, World!";
?>

<?php
  echo "This is output using echo";
  print "This is output using print";
?>

<?php
  $name = "Ali";
  $age = 25;
  echo "My name is $name and I am $age years old.";
?>

// Single-line comment
# Also single-line comment
/* Multi-line
   comment */

$name = "Ali";

$age = 30;

$price = 19.99;

$is_active = true;

$colors = array("red", "green", "blue");

var_dump($variable); // Displays type and value
is_string($name);    // Returns true if $name is a string
is_array($colors);   // Returns true if $colors is an array

$a = 10;
$b = 3;
echo $a + $b;  // Addition
echo $a - $b;  // Subtraction
echo $a * $b;  // Multiplication
echo $a / $b;  // Division
echo $a % $b;  // Modulus

$x = 5;
$x += 3; // same as $x = $x + 3

$a == $b  // Equal
$a === $b // Identical (value + type)
$a != $b  // Not equal
$a > $b   // Greater than

($a > 0 && $b > 0) // AND
($a > 0 || $b > 0) // OR
!$a               // NOT

$first = "Hello";
$second = "World";
echo $first . " " . $second;

<?php
$score = 85;

if ($score >= 90) {
    echo "Grade: A";
} elseif ($score >= 80) {
    echo "Grade: B";
} elseif ($score >= 70) {
    echo "Grade: C";
} else {
    echo "Grade: F";
}
?>

<?php
$day = "Tuesday";

switch ($day) {
    case "Monday":
        echo "Start of the week!";
        break;
    case "Friday":
        echo "Weekend is near!";
        break;
    case "Sunday":
        echo "Rest day!";
        break;
    default:
        echo "Just another day.";
}
?>

<?php
$i = 0;
while ($i < 5) {
    echo "Number: $i<br>";
    $i++;
}
?>

<?php
$i = 0;
do {
    echo "Count: $i<br>";
    $i++;
} while ($i < 3);
?>

<?php
for ($i = 1; $i <= 5; $i++) {
    echo "Line $i<br>";
}
?>

<?php
$colors = array("red", "green", "blue");
foreach ($colors as $color) {
    echo "Color: $color<br>";
}
?>

<?php
$person = array("name" => "Ali", "age" => 28);
foreach ($person as $key => $value) {
    echo "$key: $value<br>";
}
?>

for ($i = 1; $i <= 5; $i++) {
    if ($i == 3) continue;
    echo "$i<br>";
}

$fruits = array("apple", "banana", "cherry");
echo $fruits[1]; // Output: banana

$fruits[] = "grape"; // Adds to the end of the array

echo count($fruits); // Output: 4

foreach ($fruits as $fruit) {
    echo $fruit . "<br>";
}

$person = array(
    "name" => "Ali",
    "age" => 30,
    "city" => "Istanbul"
);
echo $person["name"]; // Output: Ali

foreach ($person as $key => $value) {
    echo "$key: $value<br>";
}

$students = array(
    array("Ali", 90, 85),
    array("Sara", 95, 88),
    array("Omar", 78, 82)
);

echo $students[0][0]; // Output: Ali
echo $students[1][2]; // Output: 88

for ($i = 0; $i < count($students); $i++) {
    for ($j = 0; $j < count($students[$i]); $j++) {
        echo $students[$i][$j] . " ";
    }
    echo "<br>";
}

$colors = array("red", "blue", "green");
sort($colors);
print_r($colors);

function greet() {
    echo "Hello, welcome to PHP!";
}

greet(); // Call the function

function greetUser($name) {
    echo "Hello, $name!";
}

greetUser("Ali"); // Output: Hello, Ali!

function add($a, $b) {
    return $a + $b;
}

echo add(3, 5); // Output: 8

function greetLanguage($name, $lang = "English") {
    echo "Hello $name, language: $lang";
}

greetLanguage("Sara"); // Output: Hello Sara, language: English

function square($num) {
    return $num * $num;
}

$result = square(6);
echo $result; // Output: 36

$x = 5;

function showX() {
    global $x;
    echo $x;
}

showX(); // Output: 5

$square = function($n) {
    return $n * $n;
};

echo $square(4); // Output: 16

function factorial($n) {
    if ($n <= 1) return 1;
    return $n * factorial($n - 1);
}

echo factorial(5); // Output: 120