PHP Array Functions

<?php
  $prices = [100, 250, 400];

  // map — transform every element
  $withVat = array_map(fn($p) => $p * 1.13, $prices);

  // filter — keep elements that pass a test
  $cheap = array_filter($prices, fn($p) => $p < 300);

  // reduce — collapse to a single value
  $total = array_reduce($prices, fn($carry, $p) => $carry + $p, 0);
  echo $total; // 750

<?php
  echo array_sum($prices);      // 750
  echo array_product([2,3,4]);  // 24
  echo count($prices);          // 3
  echo max($prices);            // 400
  echo min($prices);            // 100

<?php
  var_dump(in_array(250, $prices));       // true
  var_dump(array_search(250, $prices));   // 1 — the key
  print_r(array_unique([1,2,2,3]));       // [1,2,3]

<?php
  $letters = ["a","b","c","d","e"];

  print_r(array_slice($letters, 1, 3));  // ["b","c","d"] — non-destructive
  array_splice($letters, 1, 2);           // removes "b","c" IN PLACE
  print_r(array_reverse([1,2,3]));        // [3,2,1]
  print_r(array_chunk([1,2,3,4,5], 2));   // [[1,2],[3,4],[5]]

<?php
  $a = [1,2,3];

  array_push($a, 4);    // add to end     → [1,2,3,4]
  array_pop($a);        // remove from end → [1,2,3]
  array_unshift($a, 0); // add to front   → [0,1,2,3]
  array_shift($a);      // remove front   → [1,2,3]

<?php
  $rows = [
      ["id" => 1, "name" => "Sita"],
      ["id" => 2, "name" => "Ram"],
  ];

  print_r(array_column($rows, "name"));         // ["Sita","Ram"]
  print_r(array_column($rows, "name", "id"));   // [1 => "Sita", 2 => "Ram"]

<?php
  $books = [
      ["title" => "B", "price" => 300],
      ["title" => "A", "price" => 150],
  ];

  usort($books, fn($x, $y) => $x['price'] <=> $y['price']);
  // now sorted by price ascending