验证美国和加拿大邮政编码的正则表达式

I am developing a stationery program. Customers have choice to pick their region either US or Canada. When they enter address they have to enter ZIP/Postal code. I am trying to validate field but I cannot use reg exp either for US or Canada. I require a regular expression that validates for both country zip code.I am developing a stationery program. Customers