If you really want to 'use this array one by one to do unix time stamp', it might pay you to change the initialization - for some reason, you're initialising the array with a hash ref (using a badly constructed hash definition, I might add) - I think you meant to write @day_Of_Month=(5,16,20); - quite what the purpose of this array is, I can't fathom from its' usage since the only reference is $day_Of_Month ... which doesn't exist.