Use object property as array key

Question

I have a PHP array of objects, say with two properties a and b. So for example I can do

$arr['a1']->a = $z;
$x = $arr['a1']->b;

The array is currently using the value of each object's a property as the array key, e.g.

$arr['a1']->a == 'a1'

This is so I can quickly look up the object by that property. I now need to quickly look up by b, and so want to switch the keys from being set to property a to being set to b (both are unique).

Is there an easy way to do this? In-place or into another array are both fine.

MatthewMcGovern · Accepted Answer · 2012-10-22 11:22:31Z

3

foreach($arr as $key => $object)
{
    $arr2[$object->b] = $object;
}

This will create a new array that points to the same objects.

If you want them in one array, you can do as Joost suggested in the comments ($arr[$object->b] = $object; in the loop instead). However, that will only work if there are no duplicate keys between the two sets.

edited Oct 22, 2012 at 11:22

answered Oct 22, 2012 at 10:52

MatthewMcGovern

3,5062 gold badges24 silver badges19 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Joost Over a year ago

Or even point to the same object with both keys ->a and ->b, assuming they are of different types or ranges..

MatthewMcGovern Over a year ago

@Joost, would that be as simple as doing $arr2[$object->b] = &$object; instead?

Joost Over a year ago

I actually ment $arr[$object->b] = $object rather than $arr2.

MatthewMcGovern Over a year ago

Ah I see, yes that would work provided the two properties combined are 100% unique, otherwise there may be some problems with an element in b over lapping an element in a.

Joost Over a year ago

Exactly. One would have to make sure they're of different types, or at least not in the same range.

|

Collectives™ on Stack Overflow

Use object property as array key

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related