an another "another variant" :

<?php
function arguments($argv)
{
  $_ARG = array();
  foreach ($argv as $arg)
  {
    if (preg_match('#^-{1,2}([a-zA-Z0-9]*)=?(.*)$#', $arg, $matches))
    {
      $key = $matches[1];
      switch ($matches[2])
      {
        case '':
        case 'true':
          $arg = true;
          break;
        case 'false':
          $arg = false;
          break;
        default:
          $arg = $matches[2];
      }
      $_ARG[$key] = $arg;
    }
    else
    {
      $_ARG['input'][] = $arg;
    }
  }
  return $_ARG;
}
?>

$php myscript.php arg1 -arg2=val2 --arg3=arg3 -arg4 --arg5 -arg6=false

Array
(
    [input] => Array
        (
            [0] => myscript.php
            [1] => arg1
        )

    [arg2] => val2
    [arg3] => arg3
    [arg4] => true
    [arg5] => true
    [arg5] => false
)