PHP variable variables

Solution 1:

Use an array instead:

An array in PHP is actually an ordered map. A map is a type that associates values to keys. This type is optimized for several different uses; it can be treated as an array, list (vector), hash table (an implementation of a map), dictionary, collection, stack, queue, and probably more. As array values can be other arrays, trees and multidimensional arrays are also possible...

Solution 2:

You should really use an array, as Gumbo wrote:

$cw = array();

for($i = 0; $i < $n; ++$i) {
    $cw[] = $something;
}

However, a solution to your problem:

for($i = 0; $i < $n; ++$i) {
    $tmp = 'cw' . $i;
    $$tmp = $something;
}