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' ?

Answer 1

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',
);

Answer 2

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.

Answer 3

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

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