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PHP Array Exercises : Sort an array according to another array as a priority list

PHP Array: Exercise-20 with Solution

Write a PHP function to sort an array according to another array acting as a priority list.

Sample Solution:

PHP Code:

<?php
function list_cmp($a, $b) 
{ 
  global $order; 

  foreach($order as $key => $value) 
    { 
      if($a==$value) 
        { 
          return 0; 
          break; 
        } 

      if($b==$value) 
        { 
          return 1; 
          break; 
        } 
    } 
} 

$order[0] = 1;
$order[1] = 3; 
$order[2] = 4; 
$order[3] = 2; 

$array[0] = 2;
$array[1] = 1; 
$array[2] = 3; 
$array[3] = 4; 
$array[4] = 2; 
$array[5] = 1; 
$array[6] = 2; 

usort($array, "list_cmp"); 

print_r($array); 
?>

Sample Output:

Array                                                       
(                                                           
    [0] => 1                                                
    [1] => 1                                                
    [2] => 3                                                
    [3] => 4                                                
    [4] => 2                                                
    [5] => 2                                                
    [6] => 2                                                
)     

Flowchart:

Flowchart: PHP - Sort an array according to another array as a priority list

PHP Code Editor:

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Next: Write a PHP function to sort subnets.

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PHP: Tips of the Day

PHP: Anonymous recursive PHP functions

In order for it to work, you need to pass $factorial as a reference

$factorial = function( $n ) use ( &$factorial ) {
    if( $n == 1 ) return 1;
    return $factorial( $n - 1 ) * $n;
};
print $factorial( 5 );

Ref : https://bit.ly/38dj7jm