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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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Previous: Write a PHP script to print "second" and Red from the specified array.
Next: Write a PHP function to sort subnets.

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PHP: Tips of the Day

Convert a PHP object to an associative array

Just typecast it

$array = (array) $yourObject;

From Arrays:

If an object is converted to an array, the result is an array whose elements are the object's properties. The keys are the member variable names, with a few notable exceptions: integer properties are unaccessible; private variables have the class name prepended to the variable name; protected variables have a '*' prepended to the variable name.These prepended values have null bytes on either side.

Example: Simple Object

$object = new StdClass;
$object->foo = 1;
$object->bar = 2;

var_dump( (array) $object );

Output:

array(2) {
  'foo' => int(1)
  'bar' => int(2)
}

Example: Complex Object

class Foo
{
    private $foo;
    protected $bar;
    public $baz;

    public function __construct()
    {
        $this->foo = 1;
        $this->bar = 2;
        $this->baz = new StdClass;
    }
}

var_dump( (array) new Foo );

Output (with \0s edited in for clarity):

array(3) {
  '\0Foo\0foo' => int(1)
  '\0*\0bar' => int(2)
  'baz' => class stdClass#2 (0) {}
}

Output with var_export instead of var_dump:

array (
  '' . "\0" . 'Foo' . "\0" . 'foo' => 1,
  '' . "\0" . '*' . "\0" . 'bar' => 2,
  'baz' =>
  stdClass::__set_state(array(
  )),
)

Typecasting this way will not do deep casting of the object graph and you need to apply the null bytes (as explained in the manual quote) to access any non-public attributes. So this works best when casting StdClass objects or objects with only public properties. For quick and dirty (what you asked for) it's fine.

Also see this in-depth blog post:

  • Fast PHP Object to Array conversion

Ref : https://bit.ly/3fqiV2E