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PHP Math Exercises: Round a float away from zero to a specified number of decimal places

PHP math: Exercise-8 with Solution

Write a PHP function to round a float away from zero to a specified number of decimal places.

Sample Data :
(78.78001, 2)
(8.131001, 2)
(0.586001, 4)
(-.125481, 3)
-.125481

Sample Solution:

PHP Code:

<?php
function roundout ($value, $places=0) {
if ($places < 0) { $places = 0; }
$x= pow(10, $places);
return ($value >= 0 ? ceil($value * $x):floor($value * $x)) / $x;
}
echo roundout (78.78001, 2)."\n";
echo roundout (8.131001, 2)."\n";
echo roundout (0.586001, 4)."\n";
echo roundout (-.125481, 3)."\n";
echo roundout (-.125481);
?>

Sample Output: 

78.79                                                       
8.14                                                        
0.5861                                                      
-0.126                                                      
-1

Flowchart :

Flowchart: Round a float away from zero to a specified number of decimal places

PHP Code Editor:

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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