when incrementing a numerical string with leading zeros with the '++' operator, the result is different in 4.0.6 than in eariler version of PHP. 

for example:

for($i="01";$i<="10";$i++)
{
  echo $i." ";
}

in 4.0.5 the output was
>>> 01 02 03 04 05 06 07 08 09 10

but in 4.0.6 the output is
>>> 01 2 3 4 5 6 7 8 9 10