Iterate in reverse through an array with PHP - SPL solution?
There is no ReverseArrayIterator
to do that. You can do
$reverted = new ArrayIterator(array_reverse($data));
or make that into your own custom iterator, e.g.
class ReverseArrayIterator extends ArrayIterator
{
public function __construct(array $array)
{
parent::__construct(array_reverse($array));
}
}
A slightly longer implementation that doesn't use array_reverse
but iterates the array via the standard array functions would be
class ReverseArrayIterator implements Iterator
{
private $array;
public function __construct(array $array)
{
$this->array = $array;
}
public function current()
{
return current($this->array);
}
public function next()
{
return prev($this->array);
}
public function key()
{
return key($this->array);
}
public function valid()
{
return key($this->array) !== null;
}
public function rewind()
{
end($this->array);
}
}
Here is a solution that does not copy and does not modify the array:
for (end($array); key($array)!==null; prev($array)){
$currentElement = current($array);
// ...
}
If you also want a reference to the current key:
for (end($array); ($currentKey=key($array))!==null; prev($array)){
$currentElement = current($array);
// ...
}
This works always as php array keys can never be null and is faster than any other answer given here.
$item=end($array);
do {
...
} while ($item=prev($array));