Regular expression for past dates

Can anyone give me validation rule for date attributes . I want to create validation rule for that date attribute it should not take future date it should show error message.
1 answers

Create a rule with an input parameter of type datetime. Add a decision with a statement like below

dateinputparameter <= '[%CurrentDateTime%]'

This will result in a true output when the input is in the past and a false output when the date is in the future.

Based on the outcome you can show an error or not.