Select every first array value in associative array - php

Question

I dynamically create this associative file array through a PHP script, and now I am wondering how do I select all values inside the root array?
I'll explain here in code.
This is the array that is currently getting generated everytime:
Array
(
[HTML] => Array
(
[0] => Index.php
)
[Javascript] => Array
(
[0] => Javascript.js
[1] => Jquery.js
)
[0] => New Text Document.txt
[Scripts] => Array
(
[0] => Get_Server_files.Script.php
)
[Style] => Array
(
[0] => General.css
[1] => Menu.css
[2] => Style.css
)
[images] => Array
(
[WelcomeImages] => Array
(
[0] => WelcomeImage0.png
[1] => WelcomeImage1.png
[2] => WelcomeImage2.png
[3] => WelcomeImage3.png
[4] => WelcomeImage4.png
[5] => WelcomeImage5.png
[6] => WelcomeImage6.png
)
[0] => bg.jpg
)
)
From here, how do I select every first value? As in selecting
HTML
Javascript
Scripts
Style
Images.
And not anything that is inside these arrays.
I have searched but everytime it's not quite what I would like.

Answer 1

You can use array_keys() to get the names and then use array_filter() to remove the 0 values:
$names = array_filter(array_keys($data));
print_r($names);
Output:
Array
(
[0] => HTML
[1] => Javascript
[3] => Scripts
[4] => Style
[5] => images
)
Demo.

Answer 2

Use array_keys()
$keys = array_keys($array);