Sorted:

How do I add options to a built in function, which only apply to a certain class of argument?-Collection of common programming errors

undefined method `downcase!' for 0:Fixnum in Devise-Collection of common programming errors

Object-c cannot access viewcontroller-Collection of common programming errors

problem about incomplete-type-Collection of common programming errors

'Undefined index' error when using foreach loop-Collection of common programming errors

Error with Rake DB:Migrate undefined method `confirm_within=' for Devise:Module-Collection of common programming errors

How to never feel humiliation?-Collection of common programming errors

Undefined Index with WordPress theme options panel-Collection of common programming errors

Bit shift compiler bug or a corner case?-Collection of common programming errors

I get an error message when trying to send an e-mail with a rar attachment. Can you help me?-Collection of common programming errors