arr-cheatsheet.php

arr-cheatsheet.php

<?php
/**
 * Cheatsheet with PHP array functions
 * 
 * Cheatsheet for showing some "use cases" about
 * PHP array functions, sorting, editing, map, filter etc.
 * 
 * @author Roberto Butti
 * @link https://gist.github.com/roberto-butti/e8a1f5a4bae04b3a9668896ac546a24c
 * 
 */

/**
 * Print a line for string, integer, array, boolean.
 */
function print_result(mixed $something): void
{
    switch (gettype($something)) {
        case 'string':
            echo "STRING  : " . $something . PHP_EOL;
            break;
        case 'integer':
            echo "INTEGER : " . $something . PHP_EOL;
            break;
        case 'array':
            echo "ARRAY   : " . implode(",", $something) . PHP_EOL;
            break;
        case 'boolean':
            echo "BOOLEAN : " . (($something) ? "true" : "false") . PHP_EOL;
            break;
        default:
            var_dump($something);
            break;
    }
}

// Returns a new array, appending input arrays with array unpacking
$arr = [1,2,3,4,5];
$output = [...$arr, ...[10,11,12]];
print_result($output);
// ARRAY   : 1,2,3,4,5,10,11,12
// Returns a new array, appending input arrays with array_merge
$arr = [1,2,3,4,5];
$output = array_merge($arr, [10,11,12]);
print_result($output);
// ARRAY   : 1,2,3,4,5,10,11,12

// Joins all elements into a string with a separator
$arr = [1,2,3,4,5];
$output = implode(",", $arr);
print_result($output);
// STRING  : 1,2,3,4,5

// Returns a section of an array from $start to $end
$start = 0;
$end = 3;
$arr = [1,2,3,4,5];
$output = array_slice($arr, $start, $end);
print_result($output);
// ARRAY   : 1,2,3

// Returns the index of the first occurrence of element in array
$arr = [1,2,3,4,5, 1,2,3,4,5];
$element = 4;
$output = array_search($element, $arr);
print_result($output);
// INTEGER : 3

// Returns the index of the last occurrence of element in array
$arr = [1,2,3,4,5, 1,2,3,4,5];
$element = 4;
$output = array_search(4, array_reverse($arr, true));
print_result($output);
// INTEGER : 8

// Calls function for each element of array (the array is unchanged)
$arr = [1,2,3,4,5];
$output = array_walk($arr, function ($element) {
    $double = $element * 2;
});
print_result($output);
print_result($arr);
// BOOLEAN : true
// ARRAY   : 1,2,3,4,5

// Returns true if all elements return true
$arr = [1,2,3,4,5];
$result = array_reduce($arr, fn($result, $element) => $result && ($element > 0), true);
print_result($result);
// BOOLEAN : true

// Returns true if at least one element return true
$arr = [1,2,3,4,5];
$result = array_reduce($arr, fn($result, $element) => $result || ($element >= 5), false);
print_result($result);
// BOOLEAN : true


// Returns new array, with element that matches the fn() function
$arr = [1,2,3,4,5];
$result = array_filter($arr, fn($element) => $element > 3);
print_result($result);
// ARRAY   : 4,5

// Returns new array with the results of running fn on every element
$arr = [1,2,3,4,5];
$result = array_map(fn($element) => $element + 3, $arr);
print_result($result);
// ARRAY   : 4,5,6,7,8

// Returns a flatten array of a nested array
$nestedArray = [1, [2,3], [4,5,6], 7];
$result = array_reduce($nestedArray, fn($result, $element) => array_merge($result, is_array($element) ? [...$element] : [$element]), []);
print_result($result);
// ARRAY   : 1,2,3,4,5,6,7

// Changes all elements in range to a the specified value
$arr = [1,2,3,4,5,6,7,8,9];
$start = 2;
$count = 6;
$result = array_replace($arr, array_fill($start, $count, 88));
print_result($result);
// ARRAY   : 1,2,88,88,88,88,88,88,9

// Returns a single value which is the function's accumulated result L2R
$arr = [1,2,3,4,5,6,7,8,9];
$result = array_reduce($arr, fn($result, $element) => $result + $element, 0);
print_result($result);
// INTEGER : 45

// Returns a single value which is the function's accumulated result R2L
$arr = [1,2,3,4,5,6,7,8,9];
$result = array_reduce(array_reverse($arr), fn($result, $element) => $result + $element, 0);
print_result($result);
// INTEGER : 45

// Removes and returns last element from arr
$arr = [1,2,3,4,5,6,7,8,9];
$result = array_pop($arr);
print_result($result);
print_result($arr);
// INTEGER : 9
// ARRAY   : 1,2,3,4,5,6,7,8

// Add element to start of arr and return new length
$arr = [1,2,3,4,5,6,7,8,9];
$newElement = 99;
$result = array_unshift($arr, $newElement);
print_result($result);
print_result($arr);
// INTEGER : 10
// ARRAY   : 99,1,2,3,4,5,6,7,8,9

// Adds element to the end of arr and returns new length
$arr = [1,2,3,4,5,6,7,8,9];
$newElement = 99;
$result = array_push($arr, 99);
print_result($result);
print_result($arr);
// INTEGER : 10
// ARRAY   : 1,2,3,4,5,6,7,8,9,99

// Reverse order of arr
$arr = [1,2,3,4,5,6,7,8,9];
$result = array_reverse($arr);
print_result($result);
// ARRAY   : 9,8,7,6,5,4,3,2,1

// Sort the elements of arr
$arr = [5,3,4,1,2,9,7,8,6];
$result = sort($arr);
print_result($arr);
// ARRAY   : 1,2,3,4,5,6,7,8,9

// Changes content of arr removing, replacing and adding elements
// at position $start, it removes $count elements and insert
// it returns the elements removed, and changes the $arr
$arr = [1,2,3,4,5,6,7,8,9];
$start = 4;
$count = 3;
$newElements = [70,71];
$result = array_splice($arr, $start, $count, $newElements);
print_result($result); // removed elements
print_result($arr); // changed array
// ARRAY   : 5,6,7
// ARRAY   : 1,2,3,4,70,71,8,9

// Returns a string representing arr its elements (same as arr.join(','))
$arr = [1,2,3,4,5,6,7,8,9];
$result = implode("", $arr);
print_result($result);
// STRING  : 123456789


// Returns length of arr
$arr = [1,2,3,4,5,6,7,8,9];
$result = count($arr);
print_result($result);
// INTEGER : 9

// Returns true if $arr is an array
$arr = [1,2,3,4,5,6,7,8,9];
$result = is_array($arr);
print_result($result);
// BOOLEAN : true