PHP Exercises: Filter the collection using the given callback

Last update on May 30 2022 11:41:52 (UTC/GMT +8 hours)

PHP: Exercise-89 with Solution

Write a PHP program to filter the collection using the given callback.

Sample Solution: -

PHP Code:

<?php
//Licence: https://bit.ly/2CFA5XY

function reject($items, $func)
{
    return array_values(array_diff($items, array_filter($items, $func)));
}
print_r(reject(['Green', 'Red', 'Black', 'White'], function ($item) {
    return strlen($item) > 4;
}));

?>

Sample Output:

Array
(
    [0] => Red
)

Flowchart:

PHP Code Editor:

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Previous: Write a PHP program to mutate the original array to filter out the values specified.
Next: Write a PHP program to return all elements in an given array except for the first one.

What is the difficulty level of this exercise?

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PHP: Tips of the Day

How to Sort Multi-dimensional Array by Value?

Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:

Example:

function sortByOrder($a, $b) {
    return $a['order'] - $b['order'];
}

usort($myArray, 'sortByOrder');

Starting in PHP 5.3, you can use an anonymous function:

usort($myArray, function($a, $b) {
    return $a['order'] - $b['order'];
});

And finally with PHP 7 you can use the spaceship operator:

usort($myArray, function($a, $b) {
    return $a['order'] <=> $b['order'];
});

To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero - best explained below. You can also use this for sorting on sub-elements.

usort($myArray, function($a, $b) {
    $retval = $a['order'] <=> $b['order'];
    if ($retval == 0) {
        $retval = $a['suborder'] <=> $b['suborder'];
        if ($retval == 0) {
            $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder'];
        }
    }
    return $retval;
});

If you need to retain key associations, use uasort() - see comparison of array sorting functions in the manual

Ref : https://bit.ly/3i77vCC