Query errors - Solved

Arrays

Mapping an array

The array_map() function gives us the ability to run a function for all elements in an array, without going through a foreach loop.

array_map(callback, $array);

This is useful when, for instance, you have an array of numbers and you want to do some operation on each number to get a new array with all the results.

$numbers = [1, 2, 3];

$squared = array_map(fn($n) => $n*$n, $numbers); // returns [1, 4, 9]

Filtering an array

The array_filter() function gives us the ability to filter out elements from an array based on a callback.

array_filter($array, callback);

This is useful when, for instance, you have an array of numbers and you want to filter out the odd numbers.

$numbers = [1, 2, 3];

$even = array_filter(
  $numbers,
	fn($n) => {
		if ($n % 2 === 0) {
			return true;
		} else {
			return false;
		}
	}
); // returns [2]

Checking if an array includes a value

The in_array() function gives us the ability to check if an element exists in the array.

in_array($value, $array);

This is useful when, for instance, you have an array of numbers and you want to see if it includes a certain number.

$numbers = [1, 2, 3];

$containsThree = in_array(3, $numbers); // returns true
$containsFour = in_array(4, $numbers); // returns false

Adding data to an array

There are two main ways to push data to an array ⬇️

$numbers = [1, 2, 3];

// the long syntax
array_push($numbers, 4);

// the short syntax
$numbers[] = 4;