Advancing pointer in a foreach loop

This is not possible because ‘foreach’ operates on a copy of the array so there is no way to do it, don’t waste your time :)
 
BUT
 
You can work around this by replacing the ‘foreach’ with a ‘while’ loop, but before you do so, you must know that the following loops are functionally identical:
 
foreach ($days as $day) {
   echo $day;
}
 
while (list(, $day) = each($days)) {
   echo $day;
}
 
The same is true for these two, they are functionally identical:
 
foreach ($days as $i => $day) {
   echo $i .': ' .$day;
}
 
while (list($i, $day) = each($days)) {
   echo $i .': ' .$day;
}
 
‘While’ used this way with ‘each’ doesn’t operate on a copy of the array so you can do something like this, replace your ‘foreach’ with a ‘while’ loop and:
 
while (list(, $token) = each($tokens)) {
   /* Skip white spaces */
   if ($token == ' ') {
      while ($token == ' ') $token = next($tokens);
   }
}