how to add elements to an array in a loop using php

Question

I am dynamically trying to populate a multidimensional array and having some trouble.

I have a list of US states. Associative array like this $states[nc], $states[sc

Answer 1

To add an element, use empty brackets.

foreach($states as $state) {
    foreach($cities as $city) {
       $data[$state][] = $city;
    }
}

This will create an array like this

array(
  'nc' => array('city1', 'city2', ...),
  'sc' => array('city1', 'city2', ...)
)

See manual under "Creating/modifying with square bracket syntax"