How to compare the date field

Hi friends,

I have a small problem, actually i have a date field , the format of the date field is "dd.mm.yyyy" but my client asked the date compareson , incase the user enters the wrong format dd/mm/yyyy that time the system shows the error message.

for example

My date format = dd.mm.yyyy => 03.03.2009

incase the user enter the wrong format => 03/05/2009 in this case the user wants the message

how to compare the date field format "dots / - '.

thanks

chinnu