How can I add numbers to an array in PHP?

One option to add an index to each element of an array is to use the array_map function. Below is an example code:

<?php
$colors = ['red', 'blue', 'green'];

$numberedColors = array_map(function($key, $value) {
    return ($key + 1) . '. ' . $value;
}, array_keys($colors), $colors);

print_r($numberedColors);
?>

The output of this will be:

Array
(
    [0] => 1. red
    [1] => 2. blue
    [2] => 3. green
)

In this example, we used the array_map function to apply an anonymous function to each element of the colors array. This anonymous function takes two parameters: $key and $value, representing the key and value of the element. The anonymous function returns a new string concatenated with the index and color name. The array_map function also takes the array returned by the array_keys function as the first parameter, allowing the anonymous function to access the correct index. Finally, we used the print_r function to print the new indexed array.