How to output array instead of a 'loop' echo return from a function?

[shamuraq]

I have a function randomly take 4 unique numbers from an array and multiply them. Problem with the script below is it only print out the products. I would like for each set of 4 numbers and its product to be in its own array and all the arrays into a main array, forming a 2 dimensional array. My current script:

//Pruning outcome from controlled lists of Prime Numbers
$primes = array(2, 3, 5, 7, 11, 13, 17, 19, 23);


function getAllCombinations($arr, $n, $selected = array(), $startIndex = 0) {
  if ($n == 0) {
    $product = 1;
    foreach ($selected as $prime) {
      $pr[] = $prime;
      $product *= $prime;
      $pr[] = $prime;
    }
    echo "Product: $product\n";
    return;
  }

  for ($i = $startIndex; $i < count($arr); $i++) {
    $selected[] = $arr[$i];
    getAllCombinations($arr, $n - 1, $selected, $i + 1);
    array_pop($selected); // Backtrack and remove the element for next iteration
  }
}  

getAllCombinations($primes, 4);

The output:

Product: 210 Product: 330 Product: 390 Product: 510, etc.

The preferred method is a 2 dimensional array as such:

[0][0] =>2 [0][1] =>3 [0][2]=>5 [0][3]=>7 and the product would be in [0][4] =>210

[1][0] =>2 [1][1] =>3 [1][2]=>5 [1][3]=>11 and the product would be in [1][4] =>330

etc.

Any pointers is greatly appreciated.

[Barand]

You've done the hard work already. Instead of calculating the product, store the selected array.

<?php
$primes = array(2, 3, 5, 7, 11, 13, 17, 19, 23);
$combos = [];

function getAllCombinations($arr, $n, &$combos, $selected = array(), $startIndex = 0) {
  if ($n == 0) {
      $combos[] = $selected;
//    $product = 1;
//    foreach ($selected as $prime) {
//      $pr[] = $prime;
//      $product *= $prime;
//      $pr[] = $prime;
//    }
//    echo "Product: $product\n";
    return;
  }

  for ($i = $startIndex; $i < count($arr); $i++) {
    $selected[] = $arr[$i];
    getAllCombinations($arr, $n - 1, $combos, $selected, $i + 1);
    array_pop($selected); // Backtrack and remove the element for next iteration
  }
}  

getAllCombinations($primes, 4, $combos);

echo '<pre>';
foreach ($combos as $com)  {
    printf("%-35s = %5d<br>", join(' &times; ', $com), array_product($com));    // output numbers and product
}

?>

giving

2 × 3 × 5 × 7     =   210
2 × 3 × 5 × 11    =   330
2 × 3 × 5 × 13    =   390
2 × 3 × 5 × 17    =   510
2 × 3 × 5 × 19    =   570
2 × 3 × 5 × 23    =   690
2 × 3 × 7 × 11    =   462
2 × 3 × 7 × 13    =   546
2 × 3 × 7 × 17    =   714
2 × 3 × 7 × 19    =   798
2 × 3 × 7 × 23    =   966
2 × 3 × 11 × 13   =   858
2 × 3 × 11 × 17   =  1122
2 × 3 × 11 × 19   =  1254
2 × 3 × 11 × 23   =  1518
2 × 3 × 13 × 17   =  1326
2 × 3 × 13 × 19   =  1482
2 × 3 × 13 × 23   =  1794
2 × 3 × 17 × 19   =  1938
2 × 3 × 17 × 23   =  2346
2 × 3 × 19 × 23   =  2622
2 × 5 × 7 × 11    =   770
2 × 5 × 7 × 13    =   910
.
.
5 × 17 × 19 × 23  = 37145
7 × 11 × 13 × 17  = 17017
7 × 11 × 13 × 19  = 19019
7 × 11 × 13 × 23  = 23023
7 × 11 × 17 × 19  = 24871
7 × 11 × 17 × 23  = 30107
7 × 11 × 19 × 23  = 33649
7 × 13 × 17 × 19  = 29393
7 × 13 × 17 × 23  = 35581
7 × 13 × 19 × 23  = 39767
7 × 17 × 19 × 23  = 52003
11 × 13 × 17 × 19 = 46189
11 × 13 × 17 × 23 = 55913
11 × 13 × 19 × 23 = 62491
11 × 17 × 19 × 23 = 81719
13 × 17 × 19 × 23 = 96577

 

[phppup]

If I understand correctly, you are only lacking the visual display of the array elements being multiplied.

Why not echo them accordingly. Or if you want the actual array positions then maybe adapt something or utilize var_dump.

Edited March 11 by phppup
Typos

[shamuraq]

11 hours ago, Barand said:

You've done the hard work already. Instead of calculating the product, store the selected array.

<?php
$primes = array(2, 3, 5, 7, 11, 13, 17, 19, 23);
$combos = [];

function getAllCombinations($arr, $n, &$combos, $selected = array(), $startIndex = 0) {
  if ($n == 0) {
      $combos[] = $selected;
//    $product = 1;
//    foreach ($selected as $prime) {
//      $pr[] = $prime;
//      $product *= $prime;
//      $pr[] = $prime;
//    }
//    echo "Product: $product\n";
    return;
  }

  for ($i = $startIndex; $i < count($arr); $i++) {
    $selected[] = $arr[$i];
    getAllCombinations($arr, $n - 1, $combos, $selected, $i + 1);
    array_pop($selected); // Backtrack and remove the element for next iteration
  }
}  

getAllCombinations($primes, 4, $combos);

echo '<pre>';
foreach ($combos as $com)  {
    printf("%-35s = %5d<br>", join(' &times; ', $com), array_product($com));    // output numbers and product
}

?>

giving

2 × 3 × 5 × 7     =   210
2 × 3 × 5 × 11    =   330
2 × 3 × 5 × 13    =   390
2 × 3 × 5 × 17    =   510
2 × 3 × 5 × 19    =   570
2 × 3 × 5 × 23    =   690
2 × 3 × 7 × 11    =   462
2 × 3 × 7 × 13    =   546
2 × 3 × 7 × 17    =   714
2 × 3 × 7 × 19    =   798
2 × 3 × 7 × 23    =   966
2 × 3 × 11 × 13   =   858
2 × 3 × 11 × 17   =  1122
2 × 3 × 11 × 19   =  1254
2 × 3 × 11 × 23   =  1518
2 × 3 × 13 × 17   =  1326
2 × 3 × 13 × 19   =  1482
2 × 3 × 13 × 23   =  1794
2 × 3 × 17 × 19   =  1938
2 × 3 × 17 × 23   =  2346
2 × 3 × 19 × 23   =  2622
2 × 5 × 7 × 11    =   770
2 × 5 × 7 × 13    =   910
.
.
5 × 17 × 19 × 23  = 37145
7 × 11 × 13 × 17  = 17017
7 × 11 × 13 × 19  = 19019
7 × 11 × 13 × 23  = 23023
7 × 11 × 17 × 19  = 24871
7 × 11 × 17 × 23  = 30107
7 × 11 × 19 × 23  = 33649
7 × 13 × 17 × 19  = 29393
7 × 13 × 17 × 23  = 35581
7 × 13 × 19 × 23  = 39767
7 × 17 × 19 × 23  = 52003
11 × 13 × 17 × 19 = 46189
11 × 13 × 17 × 23 = 55913
11 × 13 × 19 × 23 = 62491
11 × 17 × 19 × 23 = 81719
13 × 17 × 19 × 23 = 96577

 

Tes... Thats exactly what i wanted. But can you explain the breakdown of "%-35 = %5d <br>"?

[Barand]

Formats the output as a left-aligned 35 char wide string and a right-aligned 5 digit wide number.

https://www.php.net/printf