how do i create a variable from another variable name?

Question

ok...in php how do i do this? given the following scenario:

// array of letters
var $letters = array('a', 'b', 'c');
// loop through array and create empty arrays with names like $a, $b, $c
foreach($letters as $letter) {
    var $$letter = array();
}

Answer 1

Check out the eval() function: Eval

Answer 2

Your code was almost correct. You just need to remove 'var' on the 2nd and fifth lines.

// array of letters
$letters = array('a', 'b', 'c');
// loop through array and create empty arrays with names like $a, $b, $c
foreach($letters as $letter) {
    $$letter = array();
}

This works correctly (as you described). I tested it.

More information on variable variables here.

As an aside, I would recommend against using eval() in your PHP.

Answer 3

You probably don't want to do this. Wanting to use variable variables is usually a sign of a failure to understand data structures and/or excessive cleverness. If you really want to do this, you could say something like...

extract(array_fill_keys($letters, array()));

...but it would be best if you didn't. Using nested arrays is probably a much better idea - especially since you can just say $nested['a'][] = 5 and PHP will append the value to the array, creating one if nothing is there. Alternately, you could just say $varname['key'] = 123 and, again, PHP will auto-create the array for you.