Question

I want to combine strings in PHP. My script creates every possible combination like below.

$part1 = array('','d','n','s','g');
$part2 = array('a','e','o','oo');
$part3 = array('m','n','s','d','l','t','g','j','p');
$part4 = array('g','p','l','');
$part5 = array('g','p','l');
$part6 = array('a','e','o');
$part7 = array('d','l','r','');

$names = array();

foreach ($part1 as $letter1) {
    foreach ($part2 as $letter2) {
        foreach ($part3 as $letter3) {
            foreach ($part4 as $letter4) {
                foreach ($part5 as $letter5) {
                    foreach ($part6 as $letter6) {
                        foreach ($part7 as $letter7) {
                            $names[] = $letter1 . $letter2 . $letter3 . $letter4 . $letter5 . $letter6 . $letter7;
                        }
                    }
                }
            }
        }
    }
}

But I am not happy with my solution. I is quick and dirty code. Is there a solution wich works with a flexible number of part arrays, so I can extend the script by e.g. $part8 easiely? (without changing the loop construction)

Answer 1

Recursive one:

function buildNames( $parts, $chars = ''){
  // Nothing to do, shouldn't happen
  if( !count( $parts)){
    return array();
  }

  $names = array();
  $part = array_shift( $parts);
  // Max level, we can build final names from characters
  if( !count( $parts)){
     foreach( $part as $char){
        $names[] = $chars . $char;
     }
     return $names;
  }

  // "We need to go deeper" and build one more level with remembered chars so far
  foreach( $part as $char){
     $names = array_merge( $names, buildNames( $parts, $chars . $char));
  }

  return $names;
}

$parts = array( $part1, $part2, $part3, $part4, $part5, $part6, $part7);
$names = buildNames( $parts);

From head, from scratch, comment if something, but idea should be good