Question

There are 3 compilation errors in the init.php code:

Undefined variable $ind

Undefined variable $popsize

Undefined variable $chrom

How to solve this issue in the proper way?

main.php

include_once 'init.php';

class Individual {
    public $genes = array();
    //...
}

class Population {
    public $ind = array();
    public $ind_ptr;
    public function setIndPtr(Individual $ind) {
        $this->ind_ptr = $ind;
    }   
}

$popsize = 10;
$chrom = 5;
$pop = new Population();
$pop_ptr = new Population();

$pop = init(pop_ptr);

init.php

 function init(Population $pop_ptr) {
      $pop_ptr->setIndPtr($ind[0]);  
      for ($i = 0 ; $i < $popsize ; $i++) { 
        for ($j = 0; $j < $chrom; $j++) {
          $d = rand(0,1);
          if($d >= 0.5) {
             $pop_ptr->ind_ptr->genes[$j] = 1;
          }
          else {
             $pop_ptr->ind_ptr->genes[$j] = 0;
          } 
        }
        $pop_ptr->setIndPtr($ind[$i+1]);
      }
      $pop_ptr->setIndPtr($ind[0]);

      return $pop_ptr;
  }

Answer 1

Its a matter of scope: Variables are not shared over files, unless you make them global!

(Badly explained) variables such as

inc.php

$a=1;

main.php

include "inc.php";
print $a

would work

however

inc.php

function func()
{
 $a=1;
}

main.php

include "inc.php";
func();
print $a;

a is not available.

Hope that makes it clearer.