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PHP Challenges: Find a missing number(s) from an array

PHP Challenges - 1: Exercise-5 with Solution

Write a PHP program to find a missing number(s) from an array.

Input : 1,2,3,6,7,8

Explanation :

PHP: Find a missing number(s) from an array

Sample Solution :

PHP Code :

function missing_number($num_list)
{
 // construct a new array
$new_arr = range($num_list[0],max($num_list));                                                    
// use array_diff to find the missing elements 
return array_diff($new_arr, $num_list);

}
print_r(missing_number(array(1,2,3,6,7,8)));
print_r(missing_number(array(10,11,12,14,15,16,17)));
?>

Sample Output: 

Array                                                                                
(                                                                                    
    [3] => 4                                                                         
    [4] => 5                                                                         
)                                                                                    
Array                                                                                
(                                                                                    
    [3] => 13                                                                        
)

Flowchart:

PHP Flowchart: Find a missing number(s) from an array

PHP Code Editor:

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Previous: Write a PHP program to check if an integer is the power of another integer.
Next: Write a PHP program to find three numbers from an array such that the sum of three consecutive numbers equal to zero.

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.



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