A test to determine whether foreach or array_walk is faster

foreach_arraywalk_test.php

<?php                                                                                                                                                                                                   
// A test to determine whether foreach or array_walk is faster
$foretimes = 0;                                                                                                                                                                                         
for($i=0; $i < 10000; $i++){                                                                                                                                                                            
  $test = array_fill(0, 10000, 'test_data');                                                                                                                                                            
  $start = microtime(true);                                                                                                                                                                             
                                                                                                                                                                                                        
  foreach ($test as $key => $value)                                                                                                                                                                     
  {                                                                                                                                                                                                     
    $result[$key] = 'testdata';                                                                                                                                                                         
  }                                                                                                                                                                                                     
                                                                                                                                                                                                        
  $end = microtime(true);                                                                                                                                                                               
  $foretimes += $end - $start;                                                                                                                                                                          
}                                                                                                                                                                                                       
                                                                                                                                                                                                        
                                                                                                                                                                                                        
$walktimes = 0;                                                                                                                                                                                         
for($i=0; $i < 10000; $i++){                                                                                                                                                                            
  $test = array_fill(0, 10000, 'test_data');                                                                                                                                                            
  $start = microtime(true);                                                                                                                                                                             
                                                                                                                                                                                                        
  array_walk($test, function($value, $index)                                                                                                                                                            
  {                                                                                                                                                                                                     
    $value = 'testdata';                                                                                                                                                                                
  });                                                                                                                                                                                                   
                                                                                                                                                                                                        
  $end = microtime(true);                                                                                                                                                                               
  $walktimes += $end - $start;                                                                                                                                                                          
}                                                                                                                                                                                                       
printf("foreach time: %0.5fs\t\t%0.5fs each\n",$foretimes, $foretimes/10000);                                                                                                                           
printf("array_walk time: %0.5fs\t\t%0.5fs each\n",$walktimes, $walktimes/10000);                                                                                                                        
?>

My last testresult:
(CentOS PHP 7.0)

foreach time: 4.51693s 0.00045s each
array_walk time: 13.88269s 0.00139s each