How to remove object from array?

You can do

function unsetValue(array $array, $value, $strict = TRUE)
{
    if(($key = array_search($value, $array, $strict)) !== FALSE) {
        unset($array[$key]);
    }
    return $array;
}

You can also use spl_object_hash to create a hash for the objects and use that as array key.

However, PHP also has a native Data Structure for Object collections with SplObjectStorage:

$a = new StdClass; $a->id = 1;
$b = new StdClass; $b->id = 2;
$c = new StdClass; $c->id = 3;

$storage = new SplObjectStorage;
$storage->attach($a);
$storage->attach($b);
$storage->attach($c);
echo $storage->count(); // 3

// trying to attach same object again
$storage->attach($c);
echo $storage->count(); // still 3

var_dump( $storage->contains($b) ); // TRUE
$storage->detach($b);
var_dump( $storage->contains($b) ); // FALSE

SplObjectStorage is Traversable, so you can foreach over it as well.

On a sidenote, PHP also has native interfaces for Subject and Observer.

I agree with the answers above, but for the sake of completeness (where you may not have unique IDs to use as a key) my preferred methods of removing values from an array are as follows:

/**
 * Remove each instance of a value within an array
 * @param array $array
 * @param mixed $value
 * @return array
 */
function array_remove(&$array, $value)
{
    return array_filter($array, function($a) use($value) {
        return $a !== $value;
    });
}

/**
 * Remove each instance of an object within an array (matched on a given property, $prop)
 * @param array $array
 * @param mixed $value
 * @param string $prop
 * @return array
 */
function array_remove_object(&$array, $value, $prop)
{
    return array_filter($array, function($a) use($value, $prop) {
        return $a->$prop !== $value;
    });
}

Which are used in the following way:

$values = array(
    1, 2, 5, 3, 5, 6, 7, 1, 2, 4, 5, 6, 6, 8, 8,
);
print_r(array_remove($values, 6));

class Obj {
    public $id;
    public function __construct($id) {
        $this->id = $id;
    }
}
$objects = array(
    new Obj(1), new Obj(2), new Obj(4), new Obj(3), new Obj(6), new Obj(4), new Obj(3), new Obj(1), new Obj(5),
);
print_r(array_remove_object($objects, 1, 'id'));

 function obj_array_clean ($array, $objId)
 {
    $new = array() ;
    foreach($array as $value)
    {
        $new[$value->{$objId}] = $value;
    }
    $array = array_values($new);
    return $array;
 }

 $ext2 = obj_array_clean($ext, 'OnjId');

• It will remove the duplicate object "OnjId" from array objects $array.

Try this, will solve your problem.

class Data{
  private $arrObservers;

  public add(Observer $o) {  
    array_push($this->arrObservers,$o);  
  }    

  public remove($Observer $o) {  
    unset($this->arrObservers[$o]);  
  }  
}