🐘 PHP Lesson 05 — Arrays

1. Array Types

<?php

// Short syntax (modern)
$fruits = ["apple", "banana", "mango"];

// Old syntax
$fruits = array("apple", "banana");

// Access
echo $fruits[0];  // "apple"
echo $fruits[2];  // "mango"

?>

<?php

$person = [
    "name" => "Ko Min",
    "age"  => 25,
    "city" => "Yangon"
];

// Access
echo $person["name"];  // "Ko Min"
echo $person["age"];   // 25

?>

Multidimensional Array

<?php

$students = [
    ["name" => "Ko Min", "score" => 95],
    ["name" => "Ma Aye", "score" => 87],
    ["name" => "Ko Kyaw", "score" => 73]
];

echo $students[0]["name"];   // "Ko Min"
echo $students[1]["score"];  // 87

foreach ($students as $student) {
    echo $student["name"] . ": " . $student["score"] . "<br>";
}

?>

2. Add & Remove Elements

<?php

$arr = [1, 2, 3];

// Add to end
$arr[] = 4;              // [1,2,3,4]
array_push($arr, 5, 6);   // [1,2,3,4,5,6]

// Remove from end
array_pop($arr);         // removes 6

// Add to front
array_unshift($arr, 0);  // [0,1,2,3,4,5]

// Remove from front
array_shift($arr);        // removes 0

// Remove by key
unset($arr[2]);            // removes index 2

// Count
count($arr);               // array length

?>

3. Array Functions

4. array_map / array_filter / array_reduce

<?php

$numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

// array_map — transform
$doubled = array_map(fn($n) => $n * 2, $numbers);
// [2,4,6,8,10,12,14,16,18,20]

// array_filter — keep matching
$evens = array_filter($numbers, fn($n) => $n % 2 === 0);
// [2,4,6,8,10]

// array_reduce — single value
$sum = array_reduce($numbers, fn($carry, $n) => $carry + $n, 0);
// 55

// Sorting with usort (custom)
$students = [
    ["name" => "Ko Min", "score" => 75],
    ["name" => "Ma Aye", "score" => 95],
    ["name" => "Ko Kyaw", "score" => 60],
];

usort($students, fn($a, $b) => $b['score'] - $a['score']);
// Sorted by score descending: Ma Aye(95), Ko Min(75), Ko Kyaw(60)

?>