Array

PHP Array Function

array_change_key_case()

array_change_key_case(array $array, int $case = CASE_LOWER): array

Change key cases

Case options

CASE_UPPER
CASE_LOWER

function arrayKeyToLowercase(array $array): array
{
  return array_change_key_case($array, CASE_LOWER);
}

function arrayKeyToUppercase(array $array): array
{
  return array_change_key_case($array, CASE_UPPER);
}


$input_array = array("FirSt" => 1, "SecOnd" => 4);
print_r(array_change_key_case($input_array, CASE_UPPER));

Array
(
    [FIRST] => 1
    [SECOND] => 4
)

array_reverse()

array_reverse(array $array, bool $preserve_keys = false): array

Return an array with elements in reverse order

$input  = [
  "php", 
  4.0, 
  [
    "green",
    "red"
  ]
];
$reversed = array_reverse($input);


print_r($input);
// Array
// (
//     [0] => php
//     [1] => 4
//     [2] => Array
//         (
//             [0] => green
//             [1] => red
//         )
// )

print_r($reversed);

// Array
// (
//     [0] => Array
//         (
//             [0] => green
//             [1] => red
//         )
//     [1] => 4
//     [2] => php
// )

array_map()

array_map(?callable $callback, array $array, array ...$arrays): array

Applies the callback to the elements of the given arrays

function cube($n)
{
    return ($n * $n * $n);
}

$a = [1, 2, 3, 4, 5];
$b = array_map('cube', $a);
print_r($b);

// Array
// (
//     [0] => 1
//     [1] => 8
//     [2] => 27
//     [3] => 64
//     [4] => 125
// )

array_diff()

array_diff(array $array, array ...$arrays): array

Computes the difference of arrays

$array1 = array("a" => "green", "red", "blue", "red");
$array2 = array("b" => "green", "yellow", "red");
$result = array_diff($array1, $array2);

print_r($result);
// Array
// (
  //     [1] => blue
// )

array_diff_assoc()

array_diff_assoc(array $array, array ...$arrays): array

Computes the difference of arrays with additional index check

$array1 = array("a" => "green", "b" => "brown", "c" => "blue", "red");
$array2 = array("a" => "green", "yellow", "red");
$result = array_diff_assoc($array1, $array2);
print_r($result);
// Array
// (
//     [b] => brown
//     [c] => blue
//     [0] => red
// )

array_diff_key()

array_diff_key(array $array, array ...$arrays): array

Computes the difference of arrays using keys for comparison

$array1 = array('blue' => 1, 'red' => 2, 'green' => 3, 'purple' => 4);
$array2 = array('green' => 5, 'yellow' => 7, 'cyan' => 8);

var_dump(array_diff_key($array1, $array2));
// array(3) {
//   ["blue"]=>
//   int(1)
//   ["red"]=>
//   int(2)
//   ["purple"]=>
//   int(4)
// }

array_intersect()

array_intersect(array $array, array ...$arrays): array

Computes the intersection of arrays

$array1 = array("a" => "green", "red", "blue");
$array2 = array("b" => "green", "yellow", "red");
$result = array_intersect($array1, $array2);
print_r($result);
// Array
// (
//     [a] => green
//     [0] => red
// )

array_intersect_assoc()

array_intersect_assoc(array $array, array ...$arrays): array

Computes the intersection of arrays with additional index check

$array1 = array("a" => "green", "b" => "brown", "c" => "blue", "red");
$array2 = array("a" => "green", "b" => "yellow", "blue", "red");
$result_array = array_intersect_assoc($array1, $array2);
print_r($result_array);
// Array
// (
//     [a] => green
// )

array_intersect_key()

array_intersect_key(array $array, array ...$arrays): array

Computes the intersection of arrays using keys for comparison

$array1 = array('blue'  => 1, 'red'  => 2, 'green'  => 3, 'purple' => 4);
$array2 = array('green' => 5, 'blue' => 6, 'yellow' => 7, 'cyan'   => 8);

var_dump(array_intersect_key($array1, $array2));
// array(2) {
//   ["blue"]=>
//   int(1)
//   ["green"]=>
//   int(3)
// }

Array pointer

Function	Description
current()	Return the current element in an array
end()	Set the internal pointer of an array to its last element
key()	Fetch a key from an array
each()	Return the current key and value pair from an array and advance the array
prev()	Rewind the internal array pointer
reset()	Set the internal pointer of an array to its first element
next()	Advance the internal pointer of an array

current(), prev() and next()

$transport = array('foot', 'bike', 'car', 'plane');
$mode = current($transport); // $mode = 'foot';
$mode = next($transport);    // $mode = 'bike';
$mode = current($transport); // $mode = 'bike';
$mode = prev($transport);    // $mode = 'foot';
$mode = end($transport);     // $mode = 'plane';
$mode = current($transport); // $mode = 'plane';

$arr = array();
var_dump(current($arr)); // bool(false)

$arr = array(array());
var_dump(current($arr)); // array(0) { }

end()

$fruits = array('apple', 'banana', 'cranberry');
echo end($fruits); // cranberry

key()

$array = array(
    'fruit1' => 'apple',
    'fruit2' => 'orange',
    'fruit3' => 'grape',
    'fruit4' => 'apple',
    'fruit5' => 'apple');

// this cycle echoes all associative array
// key where value equals "apple"
while ($fruit_name = current($array)) {
    if ($fruit_name == 'apple') {
        echo key($array), "\n";
    }
    next($array);
}

// fruit1
// fruit4
// fruit5

each()

$foo = array("Robert" => "Bob", "Seppo" => "Sepi");
$bar = each($foo);
print_r($bar);

// Array
// (
//     [1] => Bob
//     [value] => Bob
//     [0] => Robert
//     [key] => Robert
// )

reset()

$array = array('step one', 'step two', 'step three', 'step four');

// by default, the pointer is on the first element
echo current($array) . "<br />\n"; // "step one"

// skip two steps
next($array);
next($array);
echo current($array) . "<br />\n"; // "step three"

// reset pointer, start again on step one
reset($array);
echo current($array) . "<br />\n"; // "step one"

Custom Helper function

Explode string and trim value into a new array

function arrayExplodeTrim(
  string $separator,
  string $string,
  int $limit = PHP_INT_MAX
): array {
  $explode_array = explode($separator, $string, $limit);
  return array_map('trim', $explode_array);
}