Multidimensional arrays

Let's continue with the topic of arrays. There is another type of array - multidimensional array. This type of array may contain another array as a value for a specific index:

$multiArray = [ 
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9],
];

Now, if we print the value with the index 0, it will be an array:

print_r($multiArray[0])

// Array
// (
//     [0] => 1
//     [1] => 2
//     [2] => 3
// )

so that we can get the value from any index from the inner array, and that will be the number:

print_r($multiArray[0][0]) // 1
print_r($multiArray[0][1]) // 2
print_r($multiArray[0][2]) // 3

We can also create an associative multidimensional array:

$people = [
    "john_doe" => [
        "name" => "John",
        "surname" => "Doe",
        "age" => 25,
    ],
    "jane_doe" => [
        "name" => "Jane",
        "surname" => "Doe",
        "age" => 25,
    ]
];

print_r($people);

// Array
// (
//     [john_doe] => Array
//         (
//             [name] => John
//             [surname] => Doe
//             [age] => 25
//         )
//     [jane_doe] => Array
//         (
//             [name] => Jane
//             [surname] => Doe
//             [age] => 25
//         )
// )

print_r($people['john_doe']['name']); // John

Tutorial By Temuri Takalandze

Exercise

Complete the code below to sum all the numbers in all inner arrays and print the result in a new line.