PHP Array Functions
map · filter · reduce · unique · flip

<?php
$nums = [1, 2, 3, 4, 5];

// Arrow function — double करो
$doubled = array_map(fn($n) => $n * 2, $nums);
print_r($doubled); // [2, 4, 6, 8, 10]

// Square करो
$squared = array_map(fn($n) => $n ** 2, $nums);
print_r($squared); // [1, 4, 9, 16, 25]

// Built-in function use करना
$names = ["rahul", "priya", "amit"];
$upper = array_map("strtoupper", $names);
print_r($upper); // [RAHUL, PRIYA, AMIT]

$proper = array_map("ucwords", $names);
print_r($proper); // [Rahul, Priya, Amit]
?>

<?php
// 1. Prices में GST add करना
$prices = [1000, 2500, 500, 1800];
$withGST = array_map(fn($p) => round($p * 1.18, 2), $prices);
print_r($withGST); // [1180, 2950, 590, 2124]

// 2. User data sanitize करना
$inputs = [" rahul ", " PRIYA ", " amit "];
$clean = array_map(
  fn($s) => ucwords(strtolower(trim($s))),
  $inputs
);
print_r($clean); // [Rahul, Priya, Amit]

// 3. Products से names extract करना
$products = [
  ["id" => 1, "name" => "PHP Book", "price" => 450],
  ["id" => 2, "name" => "Laravel", "price" => 799],
  ["id" => 3, "name" => "MySQL", "price" => 299],
];
$names = array_map(fn($p) => $p["name"], $products);
$prices = array_map(fn($p) => $p["price"], $products);
echo implode(", ", $names); // PHP Book, Laravel, MySQL

// 4. Multiple arrays एक साथ map
$a = [1, 2, 3];
$b = [10, 20, 30];
$sum = array_map(fn($x, $y) => $x + $y, $a, $b);
print_r($sum); // [11, 22, 33]
?>

<?php
$nums = [1, 2, 3, 4, 5, 6, 7, 8];

// Even numbers filter
$even = array_filter($nums, fn($n) => $n % 2 === 0);
print_r($even); // [1=>2, 3=>4, 5=>6, 7=>8] — keys preserved!

// 5 से बड़े numbers
$big = array_filter($nums, fn($n) => $n > 5);
print_r($big); // [5=>6, 6=>7, 7=>8]

// Callback के बिना — falsy values हटाओ
$mixed = [0, "PHP", "", 42, null, false, "Hello"];
$clean = array_filter($mixed); // No callback!
print_r($clean); // [1=>"PHP", 3=>42, 6=>"Hello"]

// Re-index करना — filter के बाद
$clean = array_values($clean); // [0=>"PHP", 1=>42, 2=>"Hello"]
?>

<?php
// 1. Adult users filter (18+)
$users = [
  ["naam" => "Rahul", "umar" => 25],
  ["naam" => "Priya", "umar" => 16],
  ["naam" => "Amit", "umar" => 30],
  ["naam" => "Neha", "umar" => 15],
];
$adults = array_values(array_filter(
  $users,
  fn($u) => $u["umar"] >= 18
));
// [{Rahul,25}, {Amit,30}]

// 2. Empty form fields हटाना
$formData = [
  "naam" => "Rahul",
  "phone" => "", // empty
  "email" => "r@g.com",
  "address" => " ", // only spaces
];
$filled = array_filter($formData, fn($v) => trim($v) !== "");
// ["naam"=>"Rahul", "email"=>"r@g.com"]

// 3. In-stock products
$products = [
  ["name" => "Book", "stock" => 5],
  ["name" => "Pen", "stock" => 0],
  ["name" => "Bag", "stock" => 12],
];
$inStock = array_values(array_filter(
  $products,
  fn($p) => $p["stock"] > 0
));
// [{Book,5}, {Bag,12}]
?>

<?php
$nums = [1, 2, 3, 4, 5];

// Step by step — sum
// Start: carry=0
// Step 1: carry = 0 + 1 = 1
// Step 2: carry = 1 + 2 = 3
// Step 3: carry = 3 + 3 = 6
// Step 4: carry = 6 + 4 = 10
// Step 5: carry = 10 + 5 = 15
$sum = array_reduce($nums, fn($carry, $item) => $carry + $item, 0);
echo $sum; // 15

// Product (गुणा)
$product = array_reduce($nums, fn($c, $i) => $c * $i, 1);
echo $product; // 120 (1×2×3×4×5)

// Max value
$max = array_reduce($nums, fn($c, $i) => $i > $c ? $i : $c, 0);
echo $max; // 5
?>

<?php
// 1. Cart total calculate
$cart = [
  ["name" => "PHP Book", "price" => 450, "qty" => 2],
  ["name" => "Laravel", "price" => 799, "qty" => 1],
  ["name" => "MySQL", "price" => 299, "qty" => 3],
];
$total = array_reduce(
  $cart,
  fn($carry, $item) => $carry + ($item["price"] * $item["qty"]),
  0
);
echo "Total: ₹" . number_format($total, 2); // ₹2,594.00

// 2. Group by category
$items = [
  ["name" => "Shirt", "cat" => "Clothing"],
  ["name" => "PHP Book", "cat" => "Books"],
  ["name" => "Jeans", "cat" => "Clothing"],
  ["name" => "JS Book", "cat" => "Books"],
];
$grouped = array_reduce($items, function($carry, $item) {
  $carry[$item["cat"]][] = $item["name"];
  return $carry;
}, []);
print_r($grouped);
// [Clothing=>[Shirt,Jeans], Books=>[PHP Book,JS Book]]
?>

<?php
// Basic duplicate removal
$nums = [1, 2, 2, 3, 3, 3, 4];
print_r(array_unique($nums));
// [0=>1, 1=>2, 3=>3, 6=>4] — keys preserved

// Re-index करना
$unique = array_values(array_unique($nums));
print_r($unique); // [0=>1, 1=>2, 2=>3, 3=>4]

// Strings
$tags = ["PHP", "MySQL", "PHP", "Laravel", "MySQL"];
$uniqueTags = array_values(array_unique($tags));
print_r($uniqueTags); // [PHP, MySQL, Laravel]

// Case sensitive — PHP ≠ php
$mixed = ["PHP", "php", "Php"];
print_r(array_unique($mixed)); // सब अलग माने जाएंगे!

// Case-insensitive unique के लिए:
$lower = array_map("strtolower", $mixed);
$unique = array_values(array_unique($lower));
print_r($unique); // [php] — एक ही
?>

<?php
// 1. Blog tags deduplicate
$allTags = ["PHP", "Web", "PHP", "MySQL", "Web", "Laravel"];
$uniqueTags = array_values(array_unique($allTags));
echo implode(", ", $uniqueTags); // PHP, Web, MySQL, Laravel

// 2. Unique user IDs
$viewerIds = [1, 5, 2, 1, 3, 5, 4, 2];
$unique = array_values(array_unique($viewerIds));
echo "Unique viewers: " . count($unique); // 5

// 3. Emails deduplicate (newsletter)
$emails = ["a@g.com", "b@g.com", "a@g.com", "c@g.com"];
$unique = array_values(array_unique($emails));
echo count($unique) . " unique subscribers"; // 3
?>

<?php
// Basic flip
$fruits = ["Apple", "Mango", "Banana"];
$flipped = array_flip($fruits);
print_r($flipped);
// ["Apple"=>0, "Mango"=>1, "Banana"=>2]

// Associative flip
$countryCodes = ["IN" => "India", "US" => "USA", "UK" => "England"];
$nameToCode = array_flip($countryCodes);
echo $nameToCode["India"]; // IN
echo $nameToCode["USA"]; // US

// Duplicate values — last one wins
$arr = ["a" => 1, "b" => 1, "c" => 2];
print_r(array_flip($arr));
// [1=>"b", 2=>"c"] — "a" overwritten by "b"
?>

<?php
// 1. Fast value lookup — array_flip से O(1) lookup
$allowedRoles = ["admin", "editor", "moderator"];
$roleIndex = array_flip($allowedRoles);
// {"admin"=>0, "editor"=>1, "moderator"=>2}

$userRole = "editor";
if (isset($roleIndex[$userRole])) {
  echo "✅ Valid role"; // isset is faster than in_array!
}

// 2. Error codes to messages
$messages = [
  "NOT_FOUND" => 404,
  "SERVER_ERROR" => 500,
  "FORBIDDEN" => 403,
];
$codes = array_flip($messages);
echo $codes[404]; // NOT_FOUND
echo $codes[500]; // SERVER_ERROR

// 3. Position by value (without array_search)
$students = ["Rahul", "Priya", "Amit"];
$byName = array_flip($students);
echo $byName["Priya"]; // 1 (index)
?>

<?php
$orders = [
  ["id" => 1, "amount" => 1200, "status" => "paid"],
  ["id" => 2, "amount" => 850, "status" => "pending"],
  ["id" => 3, "amount" => 2100, "status" => "paid"],
  ["id" => 4, "amount" => 450, "status" => "cancelled"],
  ["id" => 5, "amount" => 3000, "status" => "paid"],
];

// Step 1: filter — सिर्फ "paid" orders
$paidOrders = array_filter($orders, fn($o) => $o["status"] === "paid");

// Step 2: map — सिर्फ amounts extract करो
$amounts = array_map(fn($o) => $o["amount"], $paidOrders);

// Step 3: reduce — total calculate करो
$revenue = array_reduce($amounts, fn($c, $i) => $c + $i, 0);

echo "Paid orders: " . count($paidOrders); // 3
echo "Total revenue: ₹" . number_format($revenue, 2); // ₹6,300.00

// One-liner version!
$total = array_reduce(
  array_filter($orders, fn($o) => $o["status"] === "paid"),
  fn($c, $o) => $c + $o["amount"],
  0
);
echo "Revenue: ₹" . number_format($total, 2); // ₹6,300.00
?>