Assign array key's value to another key of the same array PHP

Question

Ok, so this is a super-newb question...

When creating an array, is there any way I could assign a key's value to another key in the same array?

For example:

<?php
$foobarr = array (
    0 => 'foo',
    1 => $foobarr[0] . 'bar',
);
?>

In this example $foobarr[1] holds the value 'bar'.

Any way I can do this so that $foobarr[1] == 'foobar'?

not like that no - the statement on the right of = is evaluated before it is assigned to $foobarr so within the array construct $foobarr doesn't exist yet. — Emissary, Mar 13 '13 at 13:53
What @MarkoD said. What's the problem that you're trying to solve? There's probably a way to solve it without this particular technical trick, which doesn't work in PHP. — Mark Reed, Mar 13 '13 at 13:54
@NappingRabbit of course it doesn't work, and final comma in array is not a problem — Marko D, Mar 13 '13 at 13:56

Mark Reed · Accepted Answer · 2013-03-13 13:55:05Z

You can do it if you assign the keys individually:

$foobarr = array();
$foobarr[0] = 'foo';
$foobarr[1] = $foobarr[0] . 'bar';

etc. But not all at once inside the initializer - the array doesn't exist yet in there.

nickb · Answer 2 · 2013-03-13 13:54:27Z

up vote 2 down vote

No, you can't do that, because the array hasn't been constructed yet when you try to reference it with $foobarr[0].

You could save 'foo' to another variable though, and just use that:

$foo = 'foo';
$foobarr = array (
    0 => $foo,
    1 => $foo . 'bar',
);

answered Mar 13 '13 at 13:54

nickb
36k52657

+ this is much more readable. – dfsq Mar 13 '13 at 13:55

hjpotter92 · Answer 3 · 2013-03-13 13:54:48Z

up vote 0 down vote

Sure, you'd need to reference it outside though.

$foobarr = array (
    0 => 'foo'
);
$foobarr[1] = $foobarr[0] . 'bar';

answered Mar 13 '13 at 13:54

hjpotter92
19.9k72850

3 Answers